Merge pull request 'Update Default Chat Pictures on Theme Change' (#115) from b/ui-fixes into develop

Reviewed-on: https://git.kske.dev/zdm/envoy/pulls/115
Reviewed-by: delvh <leon@kske.dev>

Jenkinsfile

@@ -0,0 +1,37 @@
+pipeline {
+	agent any
+
+	options {
+		ansiColor('xterm')
+	}
+
+	stages {
+		stage('Build') {
+			steps {
+				sh 'mvn -DskipTests clean package'
+			}
+		}
+		stage('Test') {
+			steps {
+				sh 'mvn test'
+			}
+			post {
+				always {
+					junit '*/target/surefire-reports/*.xml'
+				}
+			}
+		}
+		stage('SonarQube Analysis') {
+			steps {
+				withSonarQubeEnv('KSKE SonarQube') {
+					sh 'mvn org.sonarsource.scanner.maven:sonar-maven-plugin:3.9.1.2184:sonar'
+				}
+			}
+		}
+	}
+	post {
+		success {
+			archiveArtifacts artifacts: 'client/target/envoy-client-*-shaded.jar, server/target/envoy-server-jar-with-dependencies.jar'
+		}
+	}
+}

README.md

@@ -17,11 +17,30 @@ If you want to transfer a file to another user, you can attach it to a message.
 
 On the settings page some convenience features can be configured, as well as the color theme.
 
+Additional info on how to use Envoy can be found [here](https://git.kske.dev/zdm/envoy/wiki) in the client section.
+
+### System requirements
+
+To run Envoy, you have to install a Java Runtime Environment (JRE) of at least version 11.
+You can download an open source implementation from [here](https://jdk.java.net/15/).
+
+If you are running a Linux distribution, make sure that an emoji font like [Noto emoji](https://github.com/googlefonts/noto-emoji) is installed.
+Most major Linux distributions like Debian, Arch and Gentoo have a Noto emoji package available inside their package repositories.
+
 ## Server Administrator
 
 To set up an Envoy server, download the package from the release page.
 
-Because the project lacks external documentation for the moment, please refer to the Javadoc inside the source code to configure your Envoy instance.
+To configure the behavior of Envoy Server, please have a look at the [documentation](https://git.kske.dev/zdm/envoy/wiki), specifically the server part.
+
+### System requirements
+
+To run Envoy server, you have to install a JRE as mentioned above, as well as a database.
+In development, PostgreSQL is used, which you can download from [here](https://www.postgresql.org/download/).
+
+Look at the file `META-INF/persistence.xml` inside `envoy-server.jar` for the database configuration.
+
+After creating a database and configuring the credentials, the server will initialize the necessary tables automatically.
 
 ## Programmer
 
@@ -48,5 +67,5 @@ Envoy is organized as a Maven project that is split into three modules.
 * Non-blocking connectivity infrastructure based on `java.nio`
 * Processors to handle incoming events
 * Database connectivity
-* Databse entities
+* Database entities
 * Utility classes to check client version compatability and password validity

client/.settings/org.eclipse.jdt.core.prefs

@@ -129,364 +129,4 @@ org.eclipse.jdt.core.compiler.problem.unusedWarningToken=warning
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-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_multiple_local_declarations=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_parameterized_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_superinterfaces=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_switch_case_expressions=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_type_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_type_parameters=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_ellipsis=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_lambda_arrow=insert
-org.eclipse.jdt.core.formatter.insert_space_before_logical_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_multiplicative_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_angle_bracket_in_parameterized_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_angle_bracket_in_type_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_angle_bracket_in_type_parameters=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_annotation_type_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_anonymous_type_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_array_initializer=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_block=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_constructor_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_enum_constant=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_enum_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_method_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_switch=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_type_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_bracket_in_array_allocation_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_bracket_in_array_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_bracket_in_array_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_annotation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_annotation_type_member_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_catch=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_constructor_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_enum_constant=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_for=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_if=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_method_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_method_invocation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_parenthesized_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_switch=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_synchronized=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_try=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_while=insert
-org.eclipse.jdt.core.formatter.insert_space_before_parenthesized_expression_in_return=insert
-org.eclipse.jdt.core.formatter.insert_space_before_parenthesized_expression_in_throw=insert
-org.eclipse.jdt.core.formatter.insert_space_before_postfix_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_prefix_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_question_in_conditional=insert
-org.eclipse.jdt.core.formatter.insert_space_before_question_in_wildcard=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_relational_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_semicolon=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_semicolon_in_for=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_semicolon_in_try_resources=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_shift_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_string_concatenation=insert
-org.eclipse.jdt.core.formatter.insert_space_before_unary_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_brackets_in_array_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_braces_in_array_initializer=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_brackets_in_array_allocation_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_annotation_type_member_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_constructor_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_enum_constant=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_method_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_method_invocation=do not insert
-org.eclipse.jdt.core.formatter.join_lines_in_comments=false
-org.eclipse.jdt.core.formatter.join_wrapped_lines=true
-org.eclipse.jdt.core.formatter.keep_annotation_declaration_on_one_line=one_line_if_single_item
-org.eclipse.jdt.core.formatter.keep_anonymous_type_declaration_on_one_line=one_line_never
-org.eclipse.jdt.core.formatter.keep_code_block_on_one_line=one_line_if_empty
-org.eclipse.jdt.core.formatter.keep_else_statement_on_same_line=true
-org.eclipse.jdt.core.formatter.keep_empty_array_initializer_on_one_line=false
-org.eclipse.jdt.core.formatter.keep_enum_constant_declaration_on_one_line=one_line_never
-org.eclipse.jdt.core.formatter.keep_enum_declaration_on_one_line=one_line_if_empty
-org.eclipse.jdt.core.formatter.keep_if_then_body_block_on_one_line=one_line_if_single_item
-org.eclipse.jdt.core.formatter.keep_imple_if_on_one_line=false
-org.eclipse.jdt.core.formatter.keep_lambda_body_block_on_one_line=one_line_always
-org.eclipse.jdt.core.formatter.keep_loop_body_block_on_one_line=one_line_if_empty
-org.eclipse.jdt.core.formatter.keep_method_body_on_one_line=one_line_if_single_item
-org.eclipse.jdt.core.formatter.keep_simple_do_while_body_on_same_line=false
-org.eclipse.jdt.core.formatter.keep_simple_for_body_on_same_line=false
-org.eclipse.jdt.core.formatter.keep_simple_getter_setter_on_one_line=true
-org.eclipse.jdt.core.formatter.keep_simple_while_body_on_same_line=false
-org.eclipse.jdt.core.formatter.keep_then_statement_on_same_line=true
-org.eclipse.jdt.core.formatter.keep_type_declaration_on_one_line=one_line_if_empty
-org.eclipse.jdt.core.formatter.lineSplit=150
-org.eclipse.jdt.core.formatter.never_indent_block_comments_on_first_column=false
-org.eclipse.jdt.core.formatter.never_indent_line_comments_on_first_column=false
-org.eclipse.jdt.core.formatter.number_of_blank_lines_after_code_block=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_at_beginning_of_code_block=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_at_beginning_of_method_body=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_at_end_of_code_block=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_at_end_of_method_body=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_before_code_block=0
-org.eclipse.jdt.core.formatter.number_of_empty_lines_to_preserve=1
-org.eclipse.jdt.core.formatter.parentheses_positions_in_annotation=separate_lines_if_wrapped
-org.eclipse.jdt.core.formatter.parentheses_positions_in_catch_clause=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_enum_constant_declaration=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_for_statment=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_if_while_statement=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_lambda_declaration=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_method_delcaration=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_method_invocation=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_switch_statement=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_try_clause=common_lines
-org.eclipse.jdt.core.formatter.put_empty_statement_on_new_line=true
-org.eclipse.jdt.core.formatter.tabulation.char=tab
-org.eclipse.jdt.core.formatter.tabulation.size=4
-org.eclipse.jdt.core.formatter.text_block_indentation=0
-org.eclipse.jdt.core.formatter.use_on_off_tags=false
-org.eclipse.jdt.core.formatter.use_tabs_only_for_leading_indentations=false
-org.eclipse.jdt.core.formatter.wrap_before_additive_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_assignment_operator=false
-org.eclipse.jdt.core.formatter.wrap_before_bitwise_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_conditional_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_logical_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_multiplicative_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_or_operator_multicatch=true
-org.eclipse.jdt.core.formatter.wrap_before_relational_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_shift_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_string_concatenation=true
-org.eclipse.jdt.core.formatter.wrap_outer_expressions_when_nested=true
 org.eclipse.jdt.core.javaFormatter=org.eclipse.jdt.core.defaultJavaFormatter

client/pom.xml

@@ -21,12 +21,12 @@
 		<dependency>
 			<groupId>org.openjfx</groupId>
 			<artifactId>javafx-controls</artifactId>
-			<version>11.0.2</version>
+			<version>15</version>
 		</dependency>
 		<dependency>
 			<groupId>org.openjfx</groupId>
 			<artifactId>javafx-fxml</artifactId>
-			<version>11.0.2</version>
+			<version>15</version>
 		</dependency>
 	</dependencies>
 

client/src/main/java/envoy/client/Main.java

@@ -7,8 +7,8 @@ import envoy.client.ui.Startup;
 /**
  * Triggers application startup.
  * <p>
- * To allow Maven shading, the main method has to be separated from the
- * {@link Startup} class which extends {@link Application}.
+ * To allow Maven shading, the main method has to be separated from the {@link Startup} class which
+ * extends {@link Application}.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
@@ -25,8 +25,7 @@ public final class Main {
 	/**
 	 * Starts the application.
 	 *
-	 * @param args the command line arguments are processed by the
-	 *             client configuration
+	 * @param args the command line arguments are processed by the client configuration
 	 * @since Envoy Client v0.1-beta
 	 */
 	public static void main(String[] args) {

client/src/main/java/envoy/client/data/Cache.java

@@ -35,7 +35,9 @@ public final class Cache<T> implements Consumer<T>, Serializable {
 	}
 
 	@Override
-	public String toString() { return String.format("Cache[elements=" + elements + "]"); }
+	public String toString() {
+		return String.format("Cache[elements=" + elements + "]");
+	}
 
 	/**
 	 * Sets the processor to which cached elements are relayed.
@@ -52,7 +54,8 @@ public final class Cache<T> implements Consumer<T>, Serializable {
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void relay() {
-		if (processor == null) throw new IllegalStateException("Processor is not defined");
+		if (processor == null)
+			throw new IllegalStateException("Processor is not defined");
 		elements.forEach(processor::accept);
 		elements.clear();
 	}
@@ -62,5 +65,7 @@ public final class Cache<T> implements Consumer<T>, Serializable {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public void clear() { elements.clear(); }
+	public void clear() {
+		elements.clear();
+	}
 }

client/src/main/java/envoy/client/data/CacheMap.java

@@ -4,8 +4,7 @@ import java.io.Serializable;
 import java.util.*;
 
 /**
- * Stores a heterogeneous map of {@link Cache} objects with different type
- * parameters.
+ * Stores a heterogeneous map of {@link Cache} objects with different type parameters.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
@@ -24,7 +23,9 @@ public final class CacheMap implements Serializable {
 	 * @param cache the cache to store
 	 * @since Envoy Client v0.1-beta
 	 */
-	public <T> void put(Class<T> key, Cache<T> cache) { map.put(key, cache); }
+	public <T> void put(Class<T> key, Cache<T> cache) {
+		map.put(key, cache);
+	}
 
 	/**
 	 * Returns a cache mapped by a class.
@@ -34,7 +35,9 @@ public final class CacheMap implements Serializable {
 	 * @return the cache
 	 * @since Envoy Client v0.1-beta
 	 */
-	public <T> Cache<T> get(Class<T> key) { return (Cache<T>) map.get(key); }
+	public <T> Cache<T> get(Class<T> key) {
+		return (Cache<T>) map.get(key);
+	}
 
 	/**
 	 * Returns a cache mapped by a class or any of its subclasses.
@@ -64,5 +67,7 @@ public final class CacheMap implements Serializable {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public void clear() { map.values().forEach(Cache::clear); }
+	public void clear() {
+		map.values().forEach(Cache::clear);
+	}
 }

client/src/main/java/envoy/client/data/Chat.java

@@ -3,16 +3,17 @@ package envoy.client.data;
 import java.io.*;
 import java.util.*;
 
+import javafx.beans.property.*;
 import javafx.collections.*;
 
-import envoy.client.net.WriteProxy;
 import envoy.data.*;
 import envoy.data.Message.MessageStatus;
 import envoy.event.MessageStatusChange;
 
+import envoy.client.net.WriteProxy;
+
 /**
- * Represents a chat between two {@link User}s
- * as a list of {@link Message} objects.
+ * Represents a chat between two {@link User}s as a list of {@link Message} objects.
  *
  * @author Maximilian Käfer
  * @author Leon Hofmeister
@@ -21,17 +22,21 @@ import envoy.event.MessageStatusChange;
  */
 public class Chat implements Serializable {
 
-	protected final Contact recipient;
-
 	protected transient ObservableList<Message> messages = FXCollections.observableArrayList();
 
-	protected int unreadAmount;
+	protected final Contact recipient;
+
+	protected boolean	disabled;
+	protected boolean	underlyingContactDeleted;
 
 	/**
 	 * Stores the last time an {@link envoy.event.IsTyping} event has been sent.
 	 */
 	protected transient long lastWritingEvent;
 
+	protected int						unreadAmount;
+	protected static IntegerProperty	totalUnreadAmount	= new SimpleIntegerProperty();
+
 	private static final long serialVersionUID = 2L;
 
 	/**
@@ -42,11 +47,14 @@ public class Chat implements Serializable {
 	 * @param recipient the user who receives the messages
 	 * @since Envoy Client v0.1-alpha
 	 */
-	public Chat(Contact recipient) { this.recipient = recipient; }
+	public Chat(Contact recipient) {
+		this.recipient = recipient;
+	}
 
 	private void readObject(ObjectInputStream stream) throws ClassNotFoundException, IOException {
 		stream.defaultReadObject();
 		messages = FXCollections.observableList((List<Message>) stream.readObject());
+		totalUnreadAmount.set(totalUnreadAmount.get() + unreadAmount);
 	}
 
 	private void writeObject(ObjectOutputStream stream) throws IOException {
@@ -55,7 +63,14 @@ public class Chat implements Serializable {
 	}
 
 	@Override
-	public String toString() { return String.format("%s[recipient=%s,messages=%d]", getClass().getSimpleName(), recipient, messages.size()); }
+	public String toString() {
+		return String.format(
+			"%s[recipient=%s,messages=%d,disabled=%b]",
+			getClass().getSimpleName(),
+			recipient,
+			messages.size(),
+			disabled);
+	}
 
 	/**
 	 * Generates a hash code based on the recipient.
@@ -63,7 +78,9 @@ public class Chat implements Serializable {
 	 * @since Envoy Client v0.1-beta
 	 */
 	@Override
-	public int hashCode() { return Objects.hash(recipient); }
+	public int hashCode() {
+		return Objects.hash(recipient);
+	}
 
 	/**
 	 * Tests equality to another object based on the recipient.
@@ -72,39 +89,46 @@ public class Chat implements Serializable {
 	 */
 	@Override
 	public boolean equals(Object obj) {
-		if (this == obj) return true;
-		if (!(obj instanceof Chat)) return false;
-		final Chat other = (Chat) obj;
+		if (this == obj)
+			return true;
+		if (!(obj instanceof Chat))
+			return false;
+		final var other = (Chat) obj;
 		return Objects.equals(recipient, other.recipient);
 	}
 
 	/**
-	 * Sets the status of all chat messages received from the recipient to
-	 * {@code READ} starting from the bottom and stopping once a read message is
-	 * found.
+	 * Sets the status of all chat messages received from the recipient to {@code READ} starting
+	 * from the bottom and stopping once a read message is found.
 	 *
-	 * @param writeProxy the write proxy instance used to notify the server about
-	 *                   the message status changes
+	 * @param writeProxy the write proxy instance used to notify the server about the message status
+	 *                   changes
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void read(WriteProxy writeProxy) {
 		for (int i = messages.size() - 1; i >= 0; --i) {
-			final Message m = messages.get(i);
-			if (m.getSenderID() == recipient.getID()) if (m.getStatus() == MessageStatus.READ) break;
+			final var m = messages.get(i);
+			if (m.getSenderID() == recipient.getID())
+				if (m.getStatus() == MessageStatus.READ)
+					break;
 				else {
 					m.setStatus(MessageStatus.READ);
 					writeProxy.writeMessageStatusChange(new MessageStatusChange(m));
 				}
 		}
+		totalUnreadAmount.set(totalUnreadAmount.get() - unreadAmount);
 		unreadAmount = 0;
 	}
 
 	/**
-	 * @return {@code true} if the newest message received in the chat doesn't have
-	 *         the status {@code READ}
+	 * @return {@code true} if the newest message received in the chat doesn't have the status
+	 *         {@code READ}
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public boolean isUnread() { return !messages.isEmpty() && messages.get(messages.size() - 1).getStatus() != MessageStatus.READ; }
+	public boolean isUnread() {
+		return !messages.isEmpty()
+			&& messages.get(messages.size() - 1).getStatus() != MessageStatus.READ;
+	}
 
 	/**
 	 * Inserts a message at the correct place according to its creation date.
@@ -121,12 +145,32 @@ public class Chat implements Serializable {
 		messages.add(0, message);
 	}
 
+	/**
+	 * Removes the message with the given ID.
+	 *
+	 * @param messageID the ID of the message to remove
+	 * @return whether the message has been found and removed
+	 * @since Envoy Client v0.3-beta
+	 */
+	public boolean remove(long messageID) {
+		return messages.removeIf(m -> m.getID() == messageID);
+	}
+
+	/**
+	 * @return an integer property storing the total amount of unread messages
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static IntegerProperty getTotalUnreadAmount() { return totalUnreadAmount; }
+
 	/**
 	 * Increments the amount of unread messages.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	public void incrementUnreadAmount() { unreadAmount++; }
+	public void incrementUnreadAmount() {
+		++unreadAmount;
+		totalUnreadAmount.set(totalUnreadAmount.get() + 1);
+	}
 
 	/**
 	 * @return the amount of unread messages in this chat
@@ -147,8 +191,7 @@ public class Chat implements Serializable {
 	public Contact getRecipient() { return recipient; }
 
 	/**
-	 * @return the last known time a {@link envoy.event.IsTyping} event has been
-	 *         sent
+	 * @return the last known time a {@link envoy.event.IsTyping} event has been sent
 	 * @since Envoy Client v0.2-beta
 	 */
 	public long getLastWritingEvent() { return lastWritingEvent; }
@@ -158,5 +201,25 @@ public class Chat implements Serializable {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public void lastWritingEventWasNow() { lastWritingEvent = System.currentTimeMillis(); }
+	public void lastWritingEventWasNow() {
+		lastWritingEvent = System.currentTimeMillis();
+	}
+
+	/**
+	 * Determines whether messages can be sent in this chat. Should be {@code true} i.e. for chats
+	 * whose recipient deleted this client as a contact.
+	 *
+	 * @return whether this chat has been disabled
+	 * @since Envoy Client v0.3-beta
+	 */
+	public boolean isDisabled() { return disabled; }
+
+	/**
+	 * Determines whether messages can be sent in this chat. Should be true i.e. for chats whose
+	 * recipient deleted this client as a contact.
+	 *
+	 * @param disabled whether this chat should be disabled
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void setDisabled(boolean disabled) { this.disabled = disabled; }
 }

client/src/main/java/envoy/client/data/ClientConfig.java

@@ -5,8 +5,8 @@ import static java.util.function.Function.identity;
 import envoy.data.Config;
 
 /**
- * Implements a configuration specific to the Envoy Client with default values
- * and convenience methods.
+ * Implements a configuration specific to the Envoy Client with default values and convenience
+ * methods.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
@@ -20,7 +20,8 @@ public final class ClientConfig extends Config {
 	 * @since Envoy Client v0.1-beta
 	 */
 	public static ClientConfig getInstance() {
-		if (config == null) config = new ClientConfig();
+		if (config == null)
+			config = new ClientConfig();
 		return config;
 	}
 
@@ -47,5 +48,7 @@ public final class ClientConfig extends Config {
 	 * @return the amount of minutes after which the local database should be saved
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Integer getLocalDBSaveInterval() { return (Integer) items.get("localDBSaveInterval").get(); }
+	public Integer getLocalDBSaveInterval() {
+		return (Integer) items.get("localDBSaveInterval").get();
+	}
 }

client/src/main/java/envoy/client/data/Context.java

@@ -36,7 +36,8 @@ public class Context {
 	 * @since Envoy Client v0.2-beta
 	 */
 	public void initWriteProxy() {
-		if (localDB == null) throw new IllegalStateException("The LocalDB has to be initialized!");
+		if (localDB == null)
+			throw new IllegalStateException("The LocalDB has to be initialized!");
 		writeProxy = new WriteProxy(client, localDB);
 	}
 

client/src/main/java/envoy/client/data/GroupChat.java

@@ -2,14 +2,14 @@ package envoy.client.data;
 
 import java.time.Instant;
 
-import envoy.client.net.WriteProxy;
 import envoy.data.*;
 import envoy.data.Message.MessageStatus;
 import envoy.event.GroupMessageStatusChange;
 
+import envoy.client.net.WriteProxy;
+
 /**
- * Represents a chat between a user and a group
- * as a list of messages.
+ * Represents a chat between a user and a group as a list of messages.
  *
  * @author Maximilian Käfer
  * @since Envoy Client v0.1-beta
@@ -25,7 +25,7 @@ public final class GroupChat extends Chat {
 	 * @param recipient the group whose members receive the messages
 	 * @since Envoy Client v0.1-beta
 	 */
-	public GroupChat(User sender, Contact recipient) {
+	public GroupChat(User sender, Group recipient) {
 		super(recipient);
 		this.sender = sender;
 	}
@@ -34,10 +34,13 @@ public final class GroupChat extends Chat {
 	public void read(WriteProxy writeProxy) {
 		for (int i = messages.size() - 1; i >= 0; --i) {
 			final GroupMessage gmsg = (GroupMessage) messages.get(i);
-			if (gmsg.getSenderID() != sender.getID()) if (gmsg.getMemberStatuses().get(sender.getID()) == MessageStatus.READ) break;
+			if (gmsg.getSenderID() != sender.getID())
+				if (gmsg.getMemberStatuses().get(sender.getID()) == MessageStatus.READ)
+					break;
 				else {
 					gmsg.getMemberStatuses().replace(sender.getID(), MessageStatus.READ);
-				writeProxy.writeMessageStatusChange(new GroupMessageStatusChange(gmsg.getID(), MessageStatus.READ, Instant.now(), sender.getID()));
+					writeProxy.writeMessageStatusChange(new GroupMessageStatusChange(gmsg.getID(),
+						MessageStatus.READ, Instant.now(), sender.getID()));
 				}
 		}
 		unreadAmount = 0;

client/src/main/java/envoy/client/data/LocalDB.java

@@ -1,35 +1,40 @@
 package envoy.client.data;
 
+import static java.util.function.Predicate.not;
+
 import java.io.*;
 import java.nio.channels.*;
 import java.nio.file.StandardOpenOption;
 import java.time.Instant;
 import java.util.*;
 import java.util.logging.*;
+import java.util.stream.Stream;
 
+import javafx.application.Platform;
 import javafx.collections.*;
 
-import envoy.client.event.*;
+import dev.kske.eventbus.core.*;
+import dev.kske.eventbus.core.Event;
+
 import envoy.data.*;
 import envoy.data.Message.MessageStatus;
 import envoy.event.*;
+import envoy.event.contact.*;
 import envoy.exception.EnvoyException;
 import envoy.util.*;
 
-import dev.kske.eventbus.Event;
-import dev.kske.eventbus.EventBus;
-import dev.kske.eventbus.EventListener;
+import envoy.client.event.*;
 
 /**
- * Stores information about the current {@link User} and their {@link Chat}s.
- * For message ID generation a {@link IDGenerator} is stored as well.
+ * Stores information about the current {@link User} and their {@link Chat}s. For message ID
+ * generation a {@link IDGenerator} is stored as well.
  * <p>
  * The managed objects are stored inside a folder in the local file system.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.3-alpha
  */
-public final class LocalDB implements EventListener {
+public final class LocalDB {
 
 	// Data
 	private User					user;
@@ -38,6 +43,7 @@ public final class LocalDB implements EventListener {
 	private IDGenerator				idGenerator;
 	private CacheMap				cacheMap	= new CacheMap();
 	private String					authToken;
+	private boolean					contactsChanged;
 
 	// Auto save timer
 	private Timer	autoSaver;
@@ -67,8 +73,11 @@ public final class LocalDB implements EventListener {
 		EventBus.getInstance().registerListener(this);
 
 		// Ensure that the database directory exists
-		if (!dbDir.exists()) dbDir.mkdirs();
-		else if (!dbDir.isDirectory()) throw new IOException(String.format("LocalDBDir '%s' is not a directory!", dbDir.getAbsolutePath()));
+		if (!dbDir.exists())
+			dbDir.mkdirs();
+		else if (!dbDir.isDirectory())
+			throw new IOException(
+				String.format("LocalDBDir '%s' is not a directory!", dbDir.getAbsolutePath()));
 
 		// Lock the directory
 		lock();
@@ -87,8 +96,7 @@ public final class LocalDB implements EventListener {
 	}
 
 	/**
-	 * Ensured that only one Envoy instance is using this local database by creating
-	 * a lock file.
+	 * Ensured that only one Envoy instance is using this local database by creating a lock file.
 	 * The lock file is deleted on application exit.
 	 *
 	 * @throws EnvoyException if the lock cannot by acquired
@@ -97,17 +105,19 @@ public final class LocalDB implements EventListener {
 	private synchronized void lock() throws EnvoyException {
 		final var file = new File(dbDir, "instance.lock");
 		try {
-			final var fc = FileChannel.open(file.toPath(), StandardOpenOption.CREATE, StandardOpenOption.WRITE);
+			final var fc = FileChannel.open(file.toPath(), StandardOpenOption.CREATE,
+				StandardOpenOption.WRITE);
 			instanceLock = fc.tryLock();
-			if (instanceLock == null) throw new EnvoyException("Another Envoy instance is using this local database!");
+			if (instanceLock == null)
+				throw new EnvoyException("Another Envoy instance is using this local database!");
 		} catch (final IOException e) {
 			throw new EnvoyException("Could not create lock file!", e);
 		}
 	}
 
 	/**
-	 * Loads the local user registry {@code users.db}, the id generator
-	 * {@code id_gen.db} and last login file {@code last_login.db}.
+	 * Loads the local user registry {@code users.db}, the id generator {@code id_gen.db} and last
+	 * login file {@code last_login.db}.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
@@ -132,10 +142,46 @@ public final class LocalDB implements EventListener {
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public synchronized void loadUserData() throws ClassNotFoundException, IOException {
-		if (user == null) throw new IllegalStateException("Client user is null, cannot initialize user storage");
+		if (user == null)
+			throw new IllegalStateException("Client user is null, cannot initialize user storage");
 		userFile = new File(dbDir, user.getID() + ".db");
 		try (var in = new ObjectInputStream(new FileInputStream(userFile))) {
+			Chat.getTotalUnreadAmount().set(0);
 			chats = FXCollections.observableList((List<Chat>) in.readObject());
+
+			// Some chats have changed and should not be overwritten by the saved values
+			if (contactsChanged) {
+				final var contacts = user.getContacts();
+
+				// Mark chats as disabled if a contact is no longer in this users contact list
+				final var changedUserChats = chats.stream()
+					.filter(not(chat -> contacts.contains(chat.getRecipient())))
+					.peek(chat -> {
+						chat.setDisabled(true);
+						logger.log(Level.INFO,
+							String.format("Deleted chat with %s.", chat.getRecipient()));
+					});
+
+				// Also update groups with a different member count
+				final var changedGroupChats =
+					contacts.stream().filter(Group.class::isInstance).flatMap(group -> {
+						final var potentialChat = getChat(group.getID());
+						if (potentialChat.isEmpty())
+							return Stream.empty();
+						final var chat = potentialChat.get();
+						if (group.getContacts().size() != chat.getRecipient().getContacts()
+							.size()) {
+							logger.log(Level.INFO, "Removed one (or more) members from " + group);
+							return Stream.of(chat);
+						} else
+							return Stream.empty();
+					});
+				Stream.concat(changedUserChats, changedGroupChats)
+					.forEach(chat -> chats.set(chats.indexOf(chat), chat));
+
+				// loadUserData can get called two (or more?) times during application lifecycle
+				contactsChanged = false;
+			}
 			cacheMap	= (CacheMap) in.readObject();
 			lastSync	= (Instant) in.readObject();
 		} finally {
@@ -144,30 +190,34 @@ public final class LocalDB implements EventListener {
 	}
 
 	/**
-	 * Synchronizes the contact list of the client user with the chat and user
-	 * storage.
+	 * Synchronizes the contact list of the client user with the chat and user storage.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
 	private void synchronize() {
-		user.getContacts().stream().filter(u -> u instanceof User && !users.containsKey(u.getName())).forEach(u -> users.put(u.getName(), (User) u));
+		user.getContacts().stream()
+			.filter(u -> u instanceof User && !users.containsKey(u.getName()))
+			.forEach(u -> users.put(u.getName(), (User) u));
 		users.put(user.getName(), user);
 
 		// Synchronize user status data
-		for (final var contact : users.values())
-			if (contact instanceof User) getChat(contact.getID()).ifPresent(chat -> { ((User) chat.getRecipient()).setStatus(contact.getStatus()); });
+		for (final var contact : user.getContacts())
+			if (contact instanceof User)
+				getChat(contact.getID()).ifPresent(chat -> {
+					((User) chat.getRecipient()).setStatus(((User) contact).getStatus());
+				});
 
 		// Create missing chats
 		user.getContacts()
 			.stream()
 			.filter(c -> !c.equals(user) && getChat(c.getID()).isEmpty())
-			.map(c -> c instanceof User ? new Chat(c) : new GroupChat(user, c))
+			.map(c -> c instanceof User ? new Chat(c) : new GroupChat(user, (Group) c))
 			.forEach(chats::add);
 	}
 
 	/**
-	 * Initializes a timer that automatically saves this local database after a
-	 * period of time specified in the settings.
+	 * Initializes a timer that automatically saves this local database after a period of time
+	 * specified in the settings.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
@@ -182,68 +232,148 @@ public final class LocalDB implements EventListener {
 		autoSaver.schedule(new TimerTask() {
 
 			@Override
-			public void run() { save(); }
+			public void run() {
+				save();
+			}
 		}, 2000, ClientConfig.getInstance().getLocalDBSaveInterval() * 60000);
 	}
 
 	/**
-	 * Stores all users. If the client user is specified, their chats will be stored
-	 * as well. The message id generator will also be saved if present.
+	 * Stores all users. If the client user is specified, their chats will be stored as well. The
+	 * message id generator will also be saved if present.
 	 *
 	 * @throws IOException if the saving process failed
 	 * @since Envoy Client v0.3-alpha
 	 */
-	@Event(eventType = EnvoyCloseEvent.class, priority = 1000)
+	@Event(EnvoyCloseEvent.class)
+	@Priority(500)
 	private synchronized void save() {
-		EnvoyLog.getLogger(LocalDB.class).log(Level.INFO, "Saving local database...");
+
+		// Stop saving if this account has been deleted
+		if (userFile == null)
+			return;
+		EnvoyLog.getLogger(LocalDB.class).log(Level.FINER, "Saving local database...");
 
 		// Save users
 		try {
 			SerializationUtils.write(usersFile, users);
 
 			// Save user data and last sync time stamp
-			if (user != null) SerializationUtils
-				.write(userFile, new ArrayList<>(chats), cacheMap, Context.getInstance().getClient().isOnline() ? Instant.now() : lastSync);
+			if (user != null)
+				SerializationUtils
+					.write(userFile, new ArrayList<>(chats), cacheMap,
+						Context.getInstance().getClient().isOnline() ? Instant.now() : lastSync);
 
 			// Save last login information
-			if (authToken != null) SerializationUtils.write(lastLoginFile, user, authToken);
+			if (authToken != null)
+				SerializationUtils.write(lastLoginFile, user, authToken);
 
 			// Save ID generator
-			if (hasIDGenerator()) SerializationUtils.write(idGeneratorFile, idGenerator);
+			if (hasIDGenerator())
+				SerializationUtils.write(idGeneratorFile, idGenerator);
 		} catch (final IOException e) {
-			EnvoyLog.getLogger(LocalDB.class).log(Level.SEVERE, "Unable to save local database: ", e);
+			EnvoyLog.getLogger(LocalDB.class).log(Level.SEVERE, "Unable to save local database: ",
+				e);
 		}
 	}
 
-	@Event(priority = 150)
-	private void onMessage(Message msg) { if (msg.getStatus() == MessageStatus.SENT) msg.nextStatus(); }
+	/**
+	 * Deletes any local remnant of this user.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void delete() {
+		try {
 
-	@Event(priority = 150)
+			// Save ID generator - can be used for other users in that db
+			if (hasIDGenerator())
+				SerializationUtils.write(idGeneratorFile, idGenerator);
+		} catch (final IOException e) {
+			EnvoyLog.getLogger(LocalDB.class).log(Level.SEVERE, "Unable to save local database: ",
+				e);
+		}
+		if (lastLoginFile != null)
+			lastLoginFile.delete();
+		userFile.delete();
+		users.remove(user.getName());
+		userFile = null;
+		onLogout();
+	}
+
+	@Event
+	@Priority(500)
+	private void onMessage(Message msg) {
+		if (msg.getStatus() == MessageStatus.SENT)
+			msg.nextStatus();
+	}
+
+	@Event
+	@Priority(500)
 	private void onGroupMessage(GroupMessage msg) {
 		// TODO: Cancel event once EventBus is updated
 		if (msg.getStatus() == MessageStatus.WAITING || msg.getStatus() == MessageStatus.READ)
 			logger.warning("The groupMessage has the unexpected status " + msg.getStatus());
 	}
 
-	@Event(priority = 150)
-	private void onMessageStatusChange(MessageStatusChange evt) { getMessage(evt.getID()).ifPresent(msg -> msg.setStatus(evt.get())); }
+	@Event
+	@Priority(500)
+	private void onMessageStatusChange(MessageStatusChange evt) {
+		getMessage(evt.getID()).ifPresent(msg -> msg.setStatus(evt.get()));
+	}
 
-	@Event(priority = 150)
+	@Event
+	@Priority(500)
 	private void onGroupMessageStatusChange(GroupMessageStatusChange evt) {
-		this.<GroupMessage>getMessage(evt.getID()).ifPresent(msg -> msg.getMemberStatuses().replace(evt.getMemberID(), evt.get()));
+		this.<GroupMessage>getMessage(evt.getID())
+			.ifPresent(msg -> msg.getMemberStatuses().replace(evt.getMemberID(), evt.get()));
 	}
 
-	@Event(priority = 150)
+	@Event
+	@Priority(500)
 	private void onUserStatusChange(UserStatusChange evt) {
-		this.getChat(evt.getID()).map(Chat::getRecipient).map(User.class::cast).ifPresent(u -> u.setStatus(evt.get()));
+		getChat(evt.getID()).map(Chat::getRecipient).map(User.class::cast)
+			.ifPresent(u -> u.setStatus(evt.get()));
 	}
 
-	@Event(priority = 150)
-	private void onGroupResize(GroupResize evt) { getChat(evt.getGroupID()).map(Chat::getRecipient).map(Group.class::cast).ifPresent(evt::apply); }
+	@Event
+	@Priority(500)
+	private void onUserOperation(UserOperation operation) {
+		final var eventUser = operation.get();
+		switch (operation.getOperationType()) {
+			case ADD:
+				Platform.runLater(() -> chats.add(0, new Chat(eventUser)));
+				break;
+			case REMOVE:
+				getChat(eventUser.getID()).ifPresent(chat -> chat.setDisabled(true));
+				break;
+		}
+	}
 
-	@Event(priority = 150)
+	@Event
+	private void onGroupCreationResult(GroupCreationResult evt) {
+		final var newGroup = evt.get();
+
+		// The group creation was not successful
+		if (newGroup == null)
+			return;
+
+		// The group was successfully created
+		else
+			Platform.runLater(() -> chats.add(new GroupChat(user, newGroup)));
+	}
+
+	@Event
+	@Priority(500)
+	private void onGroupResize(GroupResize evt) {
+		getChat(evt.getGroupID()).map(Chat::getRecipient).map(Group.class::cast)
+			.ifPresent(evt::apply);
+	}
+
+	@Event
+	@Priority(500)
 	private void onNameChange(NameChange evt) {
-		chats.stream().map(Chat::getRecipient).filter(c -> c.getID() == evt.getID()).findAny().ifPresent(c -> c.setName(evt.get()));
+		chats.stream().map(Chat::getRecipient).filter(c -> c.getID() == evt.getID()).findAny()
+			.ifPresent(c -> c.setName(evt.get()));
 	}
 
 	/**
@@ -253,14 +383,17 @@ public final class LocalDB implements EventListener {
 	 * @since Envoy Client v0.2-beta
 	 */
 	@Event
-	private void onNewAuthToken(NewAuthToken evt) { authToken = evt.get(); }
+	private void onNewAuthToken(NewAuthToken evt) {
+		authToken = evt.get();
+	}
 
 	/**
 	 * Deletes all associations to the current user.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	@Event(eventType = Logout.class, priority = 100)
+	@Event(Logout.class)
+	@Priority(50)
 	private void onLogout() {
 		autoSaver.cancel();
 		autoSaveRestart = true;
@@ -274,8 +407,53 @@ public final class LocalDB implements EventListener {
 	}
 
 	/**
-	 * @return a {@code Map<String, User>} of all users stored locally with their
-	 *         user names as keys
+	 * Deletes the message with the given ID, if present.
+	 *
+	 * @param message the event that was
+	 * @since Envoy Client v0.3-beta
+	 */
+	@Event
+	private void onMessageDeletion(MessageDeletion message) {
+		Platform.runLater(() -> {
+
+			// We suppose that messages have unique IDs, hence the search can be stopped
+			// once a message was removed
+			final var messageID = message.get();
+			for (final var chat : chats)
+				if (chat.remove(messageID))
+					break;
+		});
+	}
+
+	@Event
+	@Priority(500)
+	private void onOwnStatusChange(OwnStatusChange statusChange) {
+		user.setStatus(statusChange.get());
+	}
+
+	@Event(ContactsChangedSinceLastLogin.class)
+	@Priority(500)
+	private void onContactsChangedSinceLastLogin() {
+		contactsChanged = true;
+	}
+
+	@Event
+	@Priority(500)
+	private void onContactDisabled(ContactDisabled event) {
+		getChat(event.get().getID()).ifPresent(chat -> chat.setDisabled(true));
+	}
+
+	@Event
+	@Priority(500)
+	private void onAccountDeletion(AccountDeletion deletion) {
+		if (user.getID() == deletion.get())
+			logger.log(Level.WARNING,
+				"I have been informed by the server that I have been deleted without even knowing it...");
+		getChat(deletion.get()).ifPresent(chat -> chat.setDisabled(true));
+	}
+
+	/**
+	 * @return a {@code Map<String, User>} of all users stored locally with their user names as keys
 	 * @since Envoy Client v0.2-alpha
 	 */
 	public Map<String, User> getUsers() { return users; }
@@ -288,7 +466,8 @@ public final class LocalDB implements EventListener {
 	 * @since Envoy Client v0.1-beta
 	 */
 	public <T extends Message> Optional<T> getMessage(long id) {
-		return (Optional<T>) chats.stream().map(Chat::getMessages).flatMap(List::stream).filter(m -> m.getID() == id).findAny();
+		return (Optional<T>) chats.stream().map(Chat::getMessages).flatMap(List::stream)
+			.filter(m -> m.getID() == id).findAny();
 	}
 
 	/**
@@ -298,11 +477,12 @@ public final class LocalDB implements EventListener {
 	 * @return an optional containing the chat
 	 * @since Envoy Client v0.1-beta
 	 */
-	public Optional<Chat> getChat(long recipientID) { return chats.stream().filter(c -> c.getRecipient().getID() == recipientID).findAny(); }
+	public Optional<Chat> getChat(long recipientID) {
+		return chats.stream().filter(c -> c.getRecipient().getID() == recipientID).findAny();
+	}
 
 	/**
-	 * @return all saved {@link Chat} objects that list the client user as the
-	 *         sender
+	 * @return all saved {@link Chat} objects that list the client user as the sender
 	 * @since Envoy Client v0.1-alpha
 	 **/
 	public ObservableList<Chat> getChats() { return chats; }
@@ -329,14 +509,17 @@ public final class LocalDB implements EventListener {
 	 * @param idGenerator the message ID generator to set
 	 * @since Envoy Client v0.3-alpha
 	 */
-	@Event(priority = 150)
+	@Event
+	@Priority(150)
 	public void setIDGenerator(IDGenerator idGenerator) { this.idGenerator = idGenerator; }
 
 	/**
 	 * @return {@code true} if an {@link IDGenerator} is present
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public boolean hasIDGenerator() { return idGenerator != null; }
+	public boolean hasIDGenerator() {
+		return idGenerator != null;
+	}
 
 	/**
 	 * @return the cache map for messages and message status changes

client/src/main/java/envoy/client/data/Settings.java

@@ -5,23 +5,22 @@ import java.util.*;
 import java.util.logging.Level;
 import java.util.prefs.Preferences;
 
-import envoy.client.event.EnvoyCloseEvent;
+import dev.kske.eventbus.core.*;
+
 import envoy.util.*;
 
-import dev.kske.eventbus.*;
-import dev.kske.eventbus.EventListener;
+import envoy.client.event.EnvoyCloseEvent;
 
 /**
- * Manages all application settings, which are different objects that can be
- * changed during runtime and serialized them by using either the file system or
- * the {@link Preferences} API.
+ * Manages all application settings, which are different objects that can be changed during runtime
+ * and serialized them by using either the file system or the {@link Preferences} API.
  *
  * @author Leon Hofmeister
  * @author Maximilian Käfer
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.2-alpha
  */
-public final class Settings implements EventListener {
+public final class Settings {
 
 	// Actual settings accessible by the rest of the application
 	private Map<String, SettingsItem<?>> items;
@@ -29,7 +28,8 @@ public final class Settings implements EventListener {
 	/**
 	 * Settings are stored in this file.
 	 */
-	private static final File settingsFile = new File(ClientConfig.getInstance().getHomeDirectory(), "settings.ser");
+	private static final File settingsFile =
+		new File(ClientConfig.getInstance().getHomeDirectory(), "settings.ser");
 
 	/**
 	 * Singleton instance of this class.
@@ -37,8 +37,8 @@ public final class Settings implements EventListener {
 	private static Settings settings = new Settings();
 
 	/**
-	 * The way to instantiate the settings. Is set to private to deny other
-	 * instances of that object.
+	 * The way to instantiate the settings. Is set to private to deny other instances of that
+	 * object.
 	 *
 	 * @since Envoy Client v0.2-alpha
 	 */
@@ -68,7 +68,7 @@ public final class Settings implements EventListener {
 	 * @throws IOException if an error occurs while saving the themes
 	 * @since Envoy Client v0.2-alpha
 	 */
-	@Event(eventType = EnvoyCloseEvent.class, priority = 900)
+	@Event(EnvoyCloseEvent.class)
 	private void save() {
 		EnvoyLog.getLogger(Settings.class).log(Level.INFO, "Saving settings...");
 
@@ -76,20 +76,27 @@ public final class Settings implements EventListener {
 		try {
 			SerializationUtils.write(settingsFile, items);
 		} catch (final IOException e) {
-			EnvoyLog.getLogger(Settings.class).log(Level.SEVERE, "Unable to save settings file: ", e);
+			EnvoyLog.getLogger(Settings.class).log(Level.SEVERE, "Unable to save settings file: ",
+				e);
 		}
 	}
 
 	private void supplementDefaults() {
-		items.putIfAbsent("enterToSend", new SettingsItem<>(true, "Enter to send", "Sends a message by pressing the enter key."));
-		items.putIfAbsent("hideOnClose", new SettingsItem<>(false, "Hide on close", "Hides the chat window when it is closed."));
-		items.putIfAbsent("currentTheme", new SettingsItem<>("dark", "Current Theme Name", "The name of the currently selected theme."));
+		items.putIfAbsent("enterToSend", new SettingsItem<>(true, "Enter to send",
+			"Sends a message by pressing the enter key."));
+		items.putIfAbsent("hideOnClose",
+			new SettingsItem<>(false, "Hide on close", "Hides the chat window when it is closed."));
+		items.putIfAbsent("currentTheme", new SettingsItem<>("dark", "Current Theme Name",
+			"The name of the currently selected theme."));
 		items.putIfAbsent("downloadLocation",
-				new SettingsItem<>(new File(System.getProperty("user.home") + "/Downloads/"), "Download location",
+			new SettingsItem<>(new File(System.getProperty("user.home") + "/Downloads/"),
+				"Download location",
 				"The location where files will be saved to"));
-		items.putIfAbsent("autoSaveDownloads", new SettingsItem<>(false, "Save without asking?", "Should downloads be saved without asking?"));
+		items.putIfAbsent("autoSaveDownloads", new SettingsItem<>(false, "Save without asking?",
+			"Should downloads be saved without asking?"));
 		items.putIfAbsent("askForConfirmation",
-				new SettingsItem<>(true, "Ask for confirmation", "Will ask for confirmation before doing certain things"));
+			new SettingsItem<>(true, "Ask for confirmation",
+				"Will ask for confirmation before doing certain things"));
 	}
 
 	/**
@@ -104,7 +111,9 @@ public final class Settings implements EventListener {
 	 * @param themeName the name to set
 	 * @since Envoy Client v0.2-alpha
 	 */
-	public void setCurrentTheme(String themeName) { ((SettingsItem<String>) items.get("currentTheme")).set(themeName); }
+	public void setCurrentTheme(String themeName) {
+		((SettingsItem<String>) items.get("currentTheme")).set(themeName);
+	}
 
 	/**
 	 * @return true if the currently used theme is one of the default themes
@@ -116,9 +125,8 @@ public final class Settings implements EventListener {
 	}
 
 	/**
-	 * @return {@code true}, if pressing the {@code Enter} key suffices to send a
-	 *         message. Otherwise it has to be pressed in conjunction with the
-	 *         {@code Control} key.
+	 * @return {@code true}, if pressing the {@code Enter} key suffices to send a message. Otherwise
+	 *         it has to be pressed in conjunction with the {@code Control} key.
 	 * @since Envoy Client v0.2-alpha
 	 */
 	public Boolean isEnterToSend() { return (Boolean) items.get("enterToSend").get(); }
@@ -126,26 +134,27 @@ public final class Settings implements EventListener {
 	/**
 	 * Changes the keystrokes performed by the user to send a message.
 	 *
-	 * @param enterToSend If set to {@code true} a message can be sent by pressing
-	 *                    the {@code Enter} key. Otherwise it has to be pressed in
-	 *                    conjunction with the {@code Control} key.
+	 * @param enterToSend If set to {@code true} a message can be sent by pressing the {@code Enter}
+	 *                    key. Otherwise it has to be pressed in conjunction with the
+	 *                    {@code Control} key.
 	 * @since Envoy Client v0.2-alpha
 	 */
-	public void setEnterToSend(boolean enterToSend) { ((SettingsItem<Boolean>) items.get("enterToSend")).set(enterToSend); }
+	public void setEnterToSend(boolean enterToSend) {
+		((SettingsItem<Boolean>) items.get("enterToSend")).set(enterToSend);
+	}
 
 	/**
-	 * @return whether Envoy will prompt a dialogue before saving an
-	 *         {@link envoy.data.Attachment}
+	 * @return whether Envoy will prompt a dialogue before saving an {@link envoy.data.Attachment}
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Boolean isDownloadSavedWithoutAsking() { return (Boolean) items.get("autoSaveDownloads").get(); }
+	public Boolean isDownloadSavedWithoutAsking() {
+		return (Boolean) items.get("autoSaveDownloads").get();
+	}
 
 	/**
-	 * Sets whether Envoy will prompt a dialogue before saving an
-	 * {@link envoy.data.Attachment}.
+	 * Sets whether Envoy will prompt a dialogue before saving an {@link envoy.data.Attachment}.
 	 *
-	 * @param autosaveDownload whether a download should be saved without asking
-	 *                         before
+	 * @param autosaveDownload whether a download should be saved without asking before
 	 * @since Envoy Client v0.2-beta
 	 */
 	public void setDownloadSavedWithoutAsking(boolean autosaveDownload) {
@@ -164,7 +173,9 @@ public final class Settings implements EventListener {
 	 * @param downloadLocation the path to set
 	 * @since Envoy Client v0.2-beta
 	 */
-	public void setDownloadLocation(File downloadLocation) { ((SettingsItem<File>) items.get("downloadLocation")).set(downloadLocation); }
+	public void setDownloadLocation(File downloadLocation) {
+		((SettingsItem<File>) items.get("downloadLocation")).set(downloadLocation);
+	}
 
 	/**
 	 * @return the current on close mode.
@@ -178,21 +189,24 @@ public final class Settings implements EventListener {
 	 * @param hideOnClose whether the application should be minimized on close
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public void setHideOnClose(boolean hideOnClose) { ((SettingsItem<Boolean>) items.get("hideOnClose")).set(hideOnClose); }
+	public void setHideOnClose(boolean hideOnClose) {
+		((SettingsItem<Boolean>) items.get("hideOnClose")).set(hideOnClose);
+	}
 
 	/**
-	 * @return whether a confirmation dialog should be displayed before certain
-	 *         actions
+	 * @return whether a confirmation dialog should be displayed before certain actions
 	 * @since Envoy Client v0.2-alpha
 	 */
-	public Boolean isAskForConfirmation() { return (Boolean) items.get("askForConfirmation").get(); }
+	public Boolean isAskForConfirmation() {
+		return (Boolean) items.get("askForConfirmation").get();
+	}
 
 	/**
-	 * Changes the behavior of calling certain functionality by displaying a
-	 * confirmation dialog before executing it.
+	 * Changes the behavior of calling certain functionality by displaying a confirmation dialog
+	 * before executing it.
 	 *
-	 * @param askForConfirmation whether confirmation dialogs should be displayed
-	 *                           before certain actions
+	 * @param askForConfirmation whether confirmation dialogs should be displayed before certain
+	 *                           actions
 	 * @since Envoy Client v0.2-alpha
 	 */
 	public void setAskForConfirmation(boolean askForConfirmation) {

client/src/main/java/envoy/client/data/SettingsItem.java

@@ -1,13 +1,11 @@
 package envoy.client.data;
 
 import java.io.Serializable;
-import java.util.function.Consumer;
 
 import javax.swing.JComponent;
 
 /**
- * Encapsulates a persistent value that is directly or indirectly mutable by the
- * user.
+ * Encapsulates a persistent value that is directly or indirectly mutable by the user.
  *
  * @param <T> the type of this {@link SettingsItem}'s value
  * @author Kai S. K. Engelbart
@@ -18,14 +16,11 @@ public final class SettingsItem<T> implements Serializable {
 	private T		value;
 	private String	userFriendlyName, description;
 
-	private transient Consumer<T> changeHandler;
-
 	private static final long serialVersionUID = 1L;
 
 	/**
-	 * Initializes a {@link SettingsItem}. The default value's class will be mapped
-	 * to a {@link JComponent} that can be used to display this {@link SettingsItem}
-	 * to the user.
+	 * Initializes a {@link SettingsItem}. The default value's class will be mapped to a
+	 * {@link JComponent} that can be used to display this {@link SettingsItem} to the user.
 	 *
 	 * @param value            the default value
 	 * @param userFriendlyName the user friendly name (short)
@@ -42,17 +37,18 @@ public final class SettingsItem<T> implements Serializable {
 	 * @return the value
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public T get() { return value; }
+	public T get() {
+		return value;
+	}
 
 	/**
-	 * Changes the value of this {@link SettingsItem}. If a {@code ChangeHandler} if
-	 * defined, it will be invoked with this value.
+	 * Changes the value of this {@link SettingsItem}. If a {@code ChangeHandler} if defined, it
+	 * will be invoked with this value.
 	 *
 	 * @param value the value to set
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void set(T value) {
-		if (changeHandler != null && value != this.value) changeHandler.accept(value);
 		this.value = value;
 	}
 
@@ -66,7 +62,9 @@ public final class SettingsItem<T> implements Serializable {
 	 * @param userFriendlyName the userFriendlyName to set
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public void setUserFriendlyName(String userFriendlyName) { this.userFriendlyName = userFriendlyName; }
+	public void setUserFriendlyName(String userFriendlyName) {
+		this.userFriendlyName = userFriendlyName;
+	}
 
 	/**
 	 * @return the description
@@ -79,17 +77,4 @@ public final class SettingsItem<T> implements Serializable {
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void setDescription(String description) { this.description = description; }
-
-	/**
-	 * Sets a {@code ChangeHandler} for this {@link SettingsItem}. It will be
-	 * invoked with the current value once during the registration and every time
-	 * when the value changes.
-	 *
-	 * @param changeHandler the changeHandler to set
-	 * @since Envoy Client v0.3-alpha
-	 */
-	public void setChangeHandler(Consumer<T> changeHandler) {
-		this.changeHandler = changeHandler;
-		changeHandler.accept(value);
-	}
 }

client/src/main/java/envoy/client/data/audio/AudioPlayer.java

@@ -22,7 +22,9 @@ public final class AudioPlayer {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	public AudioPlayer() { this(AudioRecorder.DEFAULT_AUDIO_FORMAT); }
+	public AudioPlayer() {
+		this(AudioRecorder.DEFAULT_AUDIO_FORMAT);
+	}
 
 	/**
 	 * Initializes the player with a given audio format.

client/src/main/java/envoy/client/data/audio/AudioRecorder.java

@@ -20,7 +20,8 @@ public final class AudioRecorder {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	public static final AudioFormat DEFAULT_AUDIO_FORMAT = new AudioFormat(16000, 16, 1, true, false);
+	public static final AudioFormat DEFAULT_AUDIO_FORMAT =
+		new AudioFormat(16000, 16, 1, true, false);
 
 	/**
 	 * The format in which audio files will be saved.
@@ -38,7 +39,9 @@ public final class AudioRecorder {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	public AudioRecorder() { this(DEFAULT_AUDIO_FORMAT); }
+	public AudioRecorder() {
+		this(DEFAULT_AUDIO_FORMAT);
+	}
 
 	/**
 	 * Initializes the recorder with a given audio format.

client/src/main/java/envoy/client/data/commands/Callable.java

@@ -0,0 +1,20 @@
+package envoy.client.data.commands;
+
+import java.util.List;
+
+/**
+ * This interface defines an action that should be performed when a system command gets called.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.2-beta
+ */
+public interface Callable {
+
+	/**
+	 * Performs the instance specific action when a {@link SystemCommand} has been called.
+	 *
+	 * @param arguments the arguments that should be passed to the {@link SystemCommand}
+	 * @since Envoy Client v0.2-beta
+	 */
+	void call(List<String> arguments);
+}

client/src/main/java/envoy/client/data/commands/OnCall.java

@@ -1,30 +0,0 @@
-package envoy.client.data.commands;
-
-import java.util.function.Supplier;
-
-/**
- * This interface defines an action that should be performed when a system
- * command gets called.
- *
- * @author Leon Hofmeister
- * @since Envoy Client v0.2-beta
- */
-public interface OnCall {
-
-	/**
-	 * Performs class specific actions when a {@link SystemCommand} has been called.
-	 *
-	 * @since Envoy Client v0.2-beta
-	 */
-	void onCall();
-
-	/**
-	 * Performs actions that can only be performed by classes that are not
-	 * {@link SystemCommand}s when a SystemCommand has been called.
-	 *
-	 * @param consumer the action to perform when this {@link SystemCommand} has
-	 *                 been called
-	 * @since Envoy Client v0.2-beta
-	 */
-	void onCall(Supplier<Void> consumer);
-}

client/src/main/java/envoy/client/data/commands/SystemCommand.java

@@ -1,23 +1,20 @@
 package envoy.client.data.commands;
 
 import java.util.*;
-import java.util.function.*;
+import java.util.function.Consumer;
 
 /**
- * This class is the base class of all {@code SystemCommands} and contains an
- * action and a number of arguments that should be used as input for this
- * function.
- * No {@code SystemCommand} can return anything.
- * Every {@code SystemCommand} must have as argument type {@code List<String>} so
- * that the words following the indicator String can be used as input of the
- * function. This approach has one limitation:<br>
- * <b>Order matters!</b> Changing the order of arguments will likely result in
- * unexpected behavior.
+ * This class is the base class of all {@code SystemCommands} and contains an action and a number of
+ * arguments that should be used as input for this function. No {@code SystemCommand} can return
+ * anything. Every {@code SystemCommand} must have as argument type {@code List<String>} so that the
+ * words following the indicator String can be used as input of the function. This approach has one
+ * limitation:<br>
+ * <b>Order matters!</b> Changing the order of arguments will likely result in unexpected behavior.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
  */
-public final class SystemCommand implements OnCall {
+public final class SystemCommand implements Callable {
 
 	protected int relevance;
 
@@ -28,8 +25,8 @@ public final class SystemCommand implements OnCall {
 
 	/**
 	 * This function takes a {@code List<String>} as argument because automatically
-	 * {@code SystemCommand#numberOfArguments} words following the necessary command
-	 * will be put into this list.
+	 * {@code SystemCommand#numberOfArguments} words following the necessary command will be put
+	 * into this list.
 	 *
 	 * @see String#split(String)
 	 */
@@ -48,19 +45,14 @@ public final class SystemCommand implements OnCall {
 	 * @param description       the description of this {@code SystemCommand}
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommand(Consumer<List<String>> action, int numberOfArguments, List<String> defaults, String description) {
+	public SystemCommand(Consumer<List<String>> action, int numberOfArguments,
+		List<String> defaults, String description) {
 		this.numberOfArguments	= numberOfArguments;
 		this.action				= action;
 		this.defaults			= defaults == null ? new ArrayList<>() : defaults;
 		this.description		= description;
 	}
 
-	/**
-	 * @return the action that should be performed
-	 * @since Envoy Client v0.2-beta
-	 */
-	public Consumer<List<String>> getAction() { return action; }
-
 	/**
 	 * @return the argument count of the command
 	 * @since Envoy Client v0.2-beta
@@ -85,20 +77,10 @@ public final class SystemCommand implements OnCall {
 	 */
 	public void setRelevance(int relevance) { this.relevance = relevance; }
 
-	/**
-	 * Increments the relevance of this {@code SystemCommand}.
-	 */
 	@Override
-	public void onCall() { relevance++; }
-
-	/**
-	 * Increments the relevance of this {@code SystemCommand} and executes the
-	 * supplier.
-	 */
-	@Override
-	public void onCall(Supplier<Void> consumer) {
-		onCall();
-		consumer.get();
+	public void call(List<String> arguments) {
+		action.accept(arguments);
+		++relevance;
 	}
 
 	/**
@@ -108,21 +90,27 @@ public final class SystemCommand implements OnCall {
 	public List<String> getDefaults() { return defaults; }
 
 	@Override
-	public int hashCode() { return Objects.hash(action); }
+	public int hashCode() {
+		return Objects.hash(action);
+	}
 
 	@Override
 	public boolean equals(Object obj) {
-		if (this == obj) return true;
-		if (obj == null) return false;
-		if (getClass() != obj.getClass()) return false;
-		final SystemCommand other = (SystemCommand) obj;
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		final var other = (SystemCommand) obj;
 		return Objects.equals(action, other.action);
 	}
 
 	@Override
 	public String toString() {
-		return "SystemCommand [relevance=" + relevance + ", numberOfArguments=" + numberOfArguments + ", "
-				+ (action != null ? "action=" + action + ", " : "") + (description != null ? "description=" + description + ", " : "")
+		return "SystemCommand [relevance=" + relevance + ", numberOfArguments=" + numberOfArguments
+			+ ", "
+			+ (description != null ? "description=" + description + ", " : "")
 			+ (defaults != null ? "defaults=" + defaults : "") + "]";
 	}
 }

client/src/main/java/envoy/client/data/commands/SystemCommandBuilder.java

@@ -20,18 +20,21 @@ public final class SystemCommandBuilder {
 	private final SystemCommandMap commandsMap;
 
 	/**
-	 * Creates a new {@code SystemCommandsBuilder} without underlying
-	 * {@link SystemCommandMap}.
+	 * Creates a new {@code SystemCommandsBuilder} without underlying {@link SystemCommandMap}.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommandBuilder() { this(null); }
+	public SystemCommandBuilder() {
+		this(null);
+	}
 
 	/**
 	 * @param commandsMap the map to use when calling build (optional)
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommandBuilder(SystemCommandMap commandsMap) { this.commandsMap = commandsMap; }
+	public SystemCommandBuilder(SystemCommandMap commandsMap) {
+		this.commandsMap = commandsMap;
+	}
 
 	/**
 	 * @param numberOfArguments the numberOfArguments to set
@@ -104,12 +107,14 @@ public final class SystemCommandBuilder {
 	 * @return the built {@code SystemCommand}
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommand build() { return build(true); }
+	public SystemCommand build() {
+		return build(true);
+	}
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * {@code SystemCommand#numberOfArguments} will be set to 0, regardless of the
-	 * previous value.<br>
+	 * {@code SystemCommand#numberOfArguments} will be set to 0, regardless of the previous
+	 * value.<br>
 	 * At the end, this {@code SystemCommandBuilder} will be reset.
 	 *
 	 * @return the built {@code SystemCommand}
@@ -122,8 +127,8 @@ public final class SystemCommandBuilder {
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * {@code SystemCommand#numberOfArguments} will be set to use the rest of the
-	 * string as argument, regardless of the previous value.<br>
+	 * {@code SystemCommand#numberOfArguments} will be set to use the rest of the string as
+	 * argument, regardless of the previous value.<br>
 	 * At the end, this {@code SystemCommandBuilder} will be reset.
 	 *
 	 * @return the built {@code SystemCommand}
@@ -136,27 +141,25 @@ public final class SystemCommandBuilder {
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * Automatically adds the built object to the given map.
-	 * At the end, this {@code SystemCommandBuilder} <b>can</b> be reset but must
-	 * not be.
+	 * Automatically adds the built object to the given map. At the end, this
+	 * {@code SystemCommandBuilder} <b>can</b> be reset but must not be.
 	 *
-	 * @param reset whether this {@code SystemCommandBuilder} should be reset
-	 *              afterwards.<br>
-	 *              This can be useful if another command wants to execute something
-	 *              similar
+	 * @param reset whether this {@code SystemCommandBuilder} should be reset afterwards.<br>
+	 *              This can be useful if another command wants to execute something similar
 	 * @return the built {@code SystemCommand}
 	 * @since Envoy Client v0.2-beta
 	 */
 	public SystemCommand build(boolean reset) {
 		final var sc = new SystemCommand(action, numberOfArguments, defaults, description);
 		sc.setRelevance(relevance);
-		if (reset) reset();
+		if (reset)
+			reset();
 		return sc;
 	}
 
 	/**
-	 * Builds a {@code SystemCommand} based upon the previously entered data.
-	 * Automatically adds the built object to the given map.
+	 * Builds a {@code SystemCommand} based upon the previously entered data. Automatically adds the
+	 * built object to the given map.
 	 *
 	 * @param command the command under which to store the SystemCommand in the
 	 *                {@link SystemCommandMap}
@@ -164,13 +167,14 @@ public final class SystemCommandBuilder {
 	 * @throws NullPointerException if no map has been assigned to this builder
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommand build(String command) { return build(command, true); }
+	public SystemCommand build(String command) {
+		return build(command, true);
+	}
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * Automatically adds the built object to the given map.
-	 * {@code SystemCommand#numberOfArguments} will be set to 0, regardless of the
-	 * previous value.<br>
+	 * Automatically adds the built object to the given map. {@code SystemCommand#numberOfArguments}
+	 * will be set to 0, regardless of the previous value.<br>
 	 * At the end, this {@code SystemCommandBuilder} will be reset.
 	 *
 	 * @param command the command under which to store the SystemCommand in the
@@ -186,9 +190,8 @@ public final class SystemCommandBuilder {
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * Automatically adds the built object to the given map.
-	 * {@code SystemCommand#numberOfArguments} will be set to use the rest of the
-	 * string as argument, regardless of the previous value.<br>
+	 * Automatically adds the built object to the given map. {@code SystemCommand#numberOfArguments}
+	 * will be set to use the rest of the string as argument, regardless of the previous value.<br>
 	 * At the end, this {@code SystemCommandBuilder} will be reset.
 	 *
 	 * @param command the command under which to store the SystemCommand in the
@@ -204,17 +207,13 @@ public final class SystemCommandBuilder {
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * Automatically adds the built object to the given map.
-	 * At the end, this {@code SystemCommandBuilder} <b>can</b> be reset but must
-	 * not be.
+	 * Automatically adds the built object to the given map. At the end, this
+	 * {@code SystemCommandBuilder} <b>can</b> be reset but must not be.
 	 *
 	 * @param command the command under which to store the SystemCommand in the
 	 *                {@link SystemCommandMap}
-	 * @param reset   whether this {@code SystemCommandBuilder} should be reset
-	 *                afterwards.<br>
-	 *                This can be useful if another command wants to execute
-	 *                something
-	 *                similar
+	 * @param reset   whether this {@code SystemCommandBuilder} should be reset afterwards.<br>
+	 *                This can be useful if another command wants to execute something similar
 	 * @return the built {@code SystemCommand}
 	 * @throws NullPointerException if no map has been assigned to this builder
 	 * @since Envoy Client v0.2-beta
@@ -222,9 +221,12 @@ public final class SystemCommandBuilder {
 	public SystemCommand build(String command, boolean reset) {
 		final var sc = new SystemCommand(action, numberOfArguments, defaults, description);
 		sc.setRelevance(relevance);
-		if (commandsMap != null) commandsMap.add(command, sc);
-		else throw new NullPointerException("No map in SystemCommandsBuilder present");
-		if (reset) reset();
+		if (commandsMap != null)
+			commandsMap.add(command, sc);
+		else
+			throw new NullPointerException("No map in SystemCommandsBuilder present");
+		if (reset)
+			reset();
 		return sc;
 	}
 }

client/src/main/java/envoy/client/data/commands/SystemCommandMap.java

@@ -1,162 +1,243 @@
 package envoy.client.data.commands;
 
 import java.util.*;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Consumer;
 import java.util.logging.*;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
+import javafx.application.Platform;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Alert.AlertType;
+
 import envoy.util.EnvoyLog;
 
 /**
- * This class stores all {@link SystemCommand}s used.
+ * Stores all {@link SystemCommand}s used. SystemCommands can be called using an activator char and
+ * the text that needs to be present behind the activator. Additionally offers the option to request
+ * recommendations for a partial input String.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
  */
 public final class SystemCommandMap {
 
+	private final Character						activator;
 	private final Map<String, SystemCommand>	systemCommands	= new HashMap<>();
-
-	private final Pattern commandPattern = Pattern.compile("^[a-zA-Z0-9_:!\\(\\)\\?\\.\\,\\;\\-]+$");
+	private final Pattern						commandPattern	=
+		Pattern.compile("^[a-zA-Z0-9_:!/\\(\\)\\?\\.\\,\\;\\-]+$");
 
 	private static final Logger logger = EnvoyLog.getLogger(SystemCommandMap.class);
 
+	/**
+	 * Creates a new {@code SystemCommandMap} with the given char as activator. If this Character is
+	 * null, any text used as input will be treated as a system command.
+	 *
+	 * @param activator the char to use as activator for commands
+	 * @since Envoy Client v0.3-beta
+	 */
+	public SystemCommandMap(Character activator) {
+		this.activator = activator;
+	}
+
+	/**
+	 * Creates a new {@code SystemCommandMap} with '/' as activator.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	public SystemCommandMap() {
+		activator = '/';
+	}
+
 	/**
 	 * Adds a new command to the map if the command name is valid.
 	 *
-	 * @param command       the input string to execute the
-	 *                      given action
-	 * @param systemCommand the command to add - can be built using
-	 *                      {@link SystemCommandBuilder}
+	 * @param command       the input string to execute the given action
+	 * @param systemCommand the command to add - can be built using {@link SystemCommandBuilder}
 	 * @see SystemCommandMap#isValidKey(String)
 	 * @since Envoy Client v0.2-beta
 	 */
 	public void add(String command, SystemCommand systemCommand) {
-		if (isValidKey(command)) systemCommands.put(command.toLowerCase(), systemCommand);
+		if (isValidKey(command))
+			systemCommands.put(command.toLowerCase(), systemCommand);
 	}
 
 	/**
-	 * This method checks if the input String is a key in the map and returns the
-	 * wrapped System command if present.
-	 * It will return an empty optional if the value after the slash is not a key in
-	 * the map, which is a valid case (i.e. input="3/4" and "4" is not a key in the
-	 * map).
+	 * This method checks if the input String is a key in the map and returns the wrapped System
+	 * command if present.
 	 * <p>
 	 * Usage example:<br>
-	 * {@code SystemCommandMap systemCommands = new SystemCommandMap();}<br>
-	 * {@code Button button = new  Button();}
-	 * {@code systemCommands.add("example", text -> button.setText(text.get(0), 1);}<br>
+	 * {@code SystemCommandMap systemCommands = new SystemCommandMap('*');}<br>
+	 * {@code systemCommands.add("example", new SystemCommand(text -> {}, 1, null, ""));}<br>
 	 * {@code ....}<br>
-	 * user input: {@code "/example xyz ..."}<br>
+	 * user input: {@code "*example xyz ..."}<br>
 	 * {@code systemCommands.get("example xyz ...")} or
-	 * {@code systemCommands.get("/example xyz ...")}
-	 * result: {@code Optional<SystemCommand>}
+	 * {@code systemCommands.get("*example xyz ...")} result:
+	 * {@code Optional<SystemCommand>.get() != null}
 	 *
 	 * @param input the input string given by the user
 	 * @return the wrapped system command, if present
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Optional<SystemCommand> get(String input) { return Optional.ofNullable(systemCommands.get(getCommand(input.toLowerCase()))); }
+	public Optional<SystemCommand> get(String input) {
+		return Optional.ofNullable(systemCommands.get(getCommand(input.toLowerCase())));
+	}
 
 	/**
-	 * This method ensures that the "/" of a {@link SystemCommand} is stripped.<br>
-	 * It returns the command as (most likely) entered as key in the map for the
-	 * first word of the text.<br>
-	 * It should only be called on strings that contain a "/" at position 0/-1.
+	 * This method ensures that the activator of a {@link SystemCommand} is stripped.<br>
+	 * It only checks the word beginning from the first non-blank position in the input. It returns
+	 * the command as (most likely) entered as key in the map for the first word of the text.<br>
+	 * Activators in the middle of the word will be disregarded.
 	 *
 	 * @param raw the input
 	 * @return the command as entered in the map
 	 * @since Envoy Client v0.2-beta
-	 * @apiNote this method will (most likely) not return anything useful if
-	 *          whatever is entered after the slash is not a system command. Only
-	 *          exception: for recommendation purposes.
+	 * @apiNote this method will (most likely) not return anything useful if whatever is entered
+	 *          after the activator is not a system command. Only exception: for recommendation
+	 *          purposes.
 	 */
 	public String getCommand(String raw) {
 		final var trimmed = raw.stripLeading();
+
+		// Entering only the activator should not throw an error
+		if (trimmed.length() == 1 && activator != null && activator.equals(trimmed.charAt(0)))
+			return "";
+		else {
 			final var index = trimmed.indexOf(' ');
-		return trimmed.substring(trimmed.charAt(0) == '/' ? 1 : 0, index < 1 ? trimmed.length() : index);
+			return trimmed.substring(
+				activator != null && activator.equals(trimmed.charAt(0)) ? 1 : 0,
+				index < 1 ? trimmed.length() : index);
+		}
 	}
 
 	/**
-	 * Examines whether a key can be put in the map and logs it with
-	 * {@code Level.WARNING} if that key violates API constrictions.<br>
-	 * (allowed chars are <b>a-zA-Z0-9_:!()?.,;-</b>)
+	 * Examines whether a key can be put in the map and logs it with {@code Level.WARNING} if that
+	 * key violates API constrictions.<br>
+	 * (allowed chars are <b>a-zA-Z0-9_:!/()?.,;-</b>)
 	 * <p>
-	 * The approach to not throw an exception was taken so that an ugly try-catch
-	 * block for every addition to the system commands map could be avoided, an
-	 * error that should only occur during implementation and not in production.
+	 * The approach to not throw an exception was taken so that an ugly try-catch block for every
+	 * addition to the system commands map could be avoided, an error that should only occur during
+	 * implementation and not in production.
 	 *
 	 * @param command the key to examine
 	 * @return whether this key can be used in the map
 	 * @since Envoy Client v0.2-beta
 	 */
 	public boolean isValidKey(String command) {
-		final boolean valid = commandPattern.matcher(command).matches();
-		if (!valid) logger.log(Level.WARNING,
+		final var valid = commandPattern.matcher(command).matches();
+		if (!valid)
+			logger.log(Level.WARNING,
 				"The command \"" + command
-						+ "\" is not valid. As it will cause problems in execution, it will not be entered into the map. Only the characters "
+					+ "\" is not valid. As it might cause problems when executed, it will not be entered into the map. Only the characters "
 					+ commandPattern + "are allowed");
 		return valid;
 	}
 
 	/**
-	 * Takes a 'raw' string (the whole input) and checks if "/" is the first visible
-	 * character and then checks if a command is present after that "/". If that is
-	 * the case, it will be executed.
-	 * <p>
+	 * Takes a 'raw' string (the whole input) and checks if the activator is the first visible
+	 * character and then checks if a command is present after that activator. If that is the case,
+	 * it will be executed.
 	 *
 	 * @param raw the raw input string
-	 * @return whether a command could be found
+	 * @return whether a command could be found and successfully executed
 	 * @since Envoy Client v0.2-beta
 	 */
-	public boolean executeIfAnyPresent(String raw) {
+	public boolean executeIfPresent(String raw) {
+
 		// possibly a command was detected and could be executed
 		final var	raw2			= raw.stripLeading();
-		final var	commandFound	= raw2.startsWith("/") ? executeIfPresent(raw2) : false;
+		final var	commandFound	= activator == null || raw2.startsWith(activator.toString())
+			? executeAvailableCommand(raw2)
+			: false;
+
 		// the command was executed successfully - no further checking needed
-		if (commandFound) logger.log(Level.FINE, "executed system command " + getCommand(raw2));
+		if (commandFound)
+			logger.log(Level.FINE, "executed system command " + getCommand(raw2));
 		return commandFound;
 	}
 
 	/**
-	 * This method checks if the input String is a key in the map and executes the
-	 * wrapped System command if present.
-	 * Its intended usage is after a "/" has been detected in the input String.
-	 * It will do nothing if the value after the slash is not a key in
-	 * the map, which is a valid case (i.e. input="3/4" and "4" is not a key in the
-	 * map).
-	 * <p>
-	 * Usage example:<br>
-	 * {@code SystemCommandMap systemCommands = new SystemCommandMap();}<br>
-	 * {@code Button button = new Button();}<br>
-	 * {@code systemCommands.add("example", (words)-> button.setText(words.get(0), 1);}<br>
-	 * {@code ....}<br>
-	 * user input: {@code "/example xyz ..."}<br>
-	 * {@code systemCommands.executeIfPresent("example xyz ...")}
-	 * result: {@code button.getText()=="xyz"}
+	 * Retrieves the recommendations based on the current input entered.<br>
+	 * The first word is used for the recommendations and it does not matter if the activator is at
+	 * its beginning or not.<br>
+	 * If recommendations are present, the given function will be executed on the
+	 * recommendations.<br>
+	 * Otherwise nothing will be done.<br>
 	 *
-	 * @param input the input string given by the user
-	 * @return whether a command could be found
+	 * @param input  the input string
+	 * @param action the action that should be taken for the recommendations, if any are present
 	 * @since Envoy Client v0.2-beta
 	 */
-	public boolean executeIfPresent(String input) {
+	public void requestRecommendations(String input, Consumer<Set<String>> action) {
+		final var partialCommand = getCommand(input);
+
+		// Get the expected commands
+		final var recommendations = recommendCommands(partialCommand);
+		if (recommendations.isEmpty())
+			return;
+
+		// Execute the given action
+		else
+			action.accept(recommendations);
+	}
+
+	/**
+	 * This method checks if the input String is a key in the map and executes the wrapped System
+	 * command if present.
+	 * <p>
+	 * Usage example:<br>
+	 * {@code SystemCommandMap systemCommands = new SystemCommandMap('*');}<br>
+	 * {@code Button button = new Button();}<br>
+	 * {@code systemCommands.add("example", new SystemCommand(text -> {button.setText(text.get(0))},
+	 * 1, null, ""));}<br>
+	 * {@code ....}<br>
+	 * user input: {@code "*example xyz ..."}<br>
+	 * {@code systemCommands.executeIfPresent("example xyz ...")} or
+	 * {@code systemCommands.executeIfPresent("*example xyz ...")} result:
+	 * {@code button.getText()=="xyz"}
+	 *
+	 * @param input the input string given by the user
+	 * @return whether a command could be found and successfully executed
+	 * @since Envoy Client v0.2-beta
+	 */
+	private boolean executeAvailableCommand(String input) {
 		final var	command			= getCommand(input);
 		final var	value			= get(command);
+		final var	commandExecuted	= new AtomicBoolean(value.isPresent());
 		value.ifPresent(systemCommand -> {
+
 			// Splitting the String so that the leading command including the first " " is
 			// removed and only as many following words as allowed by the system command
 			// persist
 			final var arguments = extractArguments(input, systemCommand);
+
 			// Executing the function
 			try {
-				systemCommand.getAction().accept(arguments);
-				systemCommand.onCall();
+				systemCommand.call(arguments);
+			} catch (final NumberFormatException e) {
+				logger.log(Level.INFO,
+					String.format(
+						"System command %s could not be performed correctly because the user is a dumbass and could not write a parseable number.",
+						command));
+				Platform.runLater(() -> {
+					final var alert = new Alert(AlertType.ERROR);
+					alert.setContentText("Please enter a readable number as argument.");
+					alert.showAndWait();
+				});
+				commandExecuted.set(false);
 			} catch (final Exception e) {
-				logger.log(Level.WARNING, "The system command " + command + " threw an exception: ", e);
+				logger.log(Level.WARNING, "System command " + command + " threw an exception: ", e);
+				Platform.runLater(() -> {
+					final var alert = new Alert(AlertType.ERROR);
+					alert.setContentText(
+						"Could not execute system command: Internal error. Please insult the responsible programmer.");
+					alert.showAndWait();
+				});
+				commandExecuted.set(false);
 			}
 		});
-		return value.isPresent();
+		return commandExecuted.get();
 	}
 
 	/**
@@ -168,86 +249,75 @@ public final class SystemCommandMap {
 	 * @since Envoy Client v0.2-beta
 	 */
 	private List<String> extractArguments(String input, SystemCommand systemCommand) {
+
 		// no more arguments follow after the command (e.g. text = "/DABR")
 		final var indexOfSpace = input.indexOf(" ");
-		if (indexOfSpace < 0) return supplementDefaults(new String[] {}, systemCommand);
+		if (indexOfSpace < 0)
+			return supplementDefaults(new String[] {}, systemCommand);
+
 		// the arguments behind a system command
 		final var	remainingString		= input.substring(indexOfSpace + 1);
 		final var	numberOfArguments	= systemCommand.getNumberOfArguments();
+
 		// splitting those arguments and supplying default values
 		final var	textArguments		= remainingString.split(" ", -1);
-		final var	originalArguments	= numberOfArguments >= 0 ? Arrays.copyOfRange(textArguments, 0, numberOfArguments) : textArguments;
+		final var	originalArguments	=
+			numberOfArguments >= 0 ? Arrays.copyOfRange(textArguments, 0, numberOfArguments)
+				: textArguments;
 		final var	arguments			= supplementDefaults(originalArguments, systemCommand);
 		return arguments;
 	}
 
-	/**
-	 * Retrieves the recommendations based on the current input entered.<br>
-	 * The first word is used for the recommendations and
-	 * it does not matter if the "/" is at its beginning or not.<br>
-	 * If none are present, nothing will be done.<br>
-	 * Otherwise the given function will be executed on the recommendations.<br>
-	 *
-	 * @param input  the input string
-	 * @param action the action that should be taken for the recommendations, if any
-	 *               are present
-	 * @since Envoy Client v0.2-beta
-	 */
-	public void requestRecommendations(String input, Consumer<Set<String>> action) {
-		final var partialCommand = getCommand(input);
-		// Get the expected commands
-		final var recommendations = recommendCommands(partialCommand);
-		if (recommendations.isEmpty()) return;
-		// Execute the given action
-		else action.accept(recommendations);
-	}
-
 	/**
 	 * Recommends commands based upon the currently entered input.<br>
-	 * In the current implementation, all we check is whether a key contains this
-	 * input. This might be updated later on.
+	 * In the current implementation, all that gets checked is whether a key contains this input.
+	 * This might be updated later on.
 	 *
 	 * @param partialCommand the partially entered command
 	 * @return a set of all commands that match this input
 	 * @since Envoy Client v0.2-beta
 	 */
 	private Set<String> recommendCommands(String partialCommand) {
+
 		// current implementation only looks if input is contained within a command,
 		// might be updated
 		return systemCommands.keySet()
 			.stream()
 			.filter(command -> command.contains(partialCommand))
-			.sorted((command1, command2) -> Integer.compare(systemCommands.get(command1).getRelevance(), systemCommands.get(command2).getRelevance()))
+			.sorted(
+				(command1, command2) -> Integer.compare(systemCommands.get(command1).getRelevance(),
+					systemCommands.get(command2).getRelevance()))
 			.collect(Collectors.toSet());
 	}
 
 	/**
-	 *
-	 * Supplies the default values for arguments if none are present in the text for
-	 * any argument. <br>
-	 * Will only work for {@code SystemCommand}s whose argument counter is bigger
-	 * than 1.
+	 * Supplies the default values for arguments if none are present in the text for any argument.
+	 * <br>
 	 *
 	 * @param textArguments the arguments that were parsed from the text
 	 * @param toEvaluate    the system command whose default values should be used
 	 * @return the final argument list
 	 * @since Envoy Client v0.2-beta
-	 * @apiNote this method will insert an empty String if the size of the list
-	 *          given to the {@code SystemCommand} is smaller than its argument
-	 *          counter and no more text arguments could be found.
+	 * @apiNote this method will insert an empty String if the size of the list given to the
+	 *          {@code SystemCommand} is smaller than its argument counter and no more text
+	 *          arguments could be found.
 	 */
 	private List<String> supplementDefaults(String[] textArguments, SystemCommand toEvaluate) {
 		final var			defaults			= toEvaluate.getDefaults();
 		final var			numberOfArguments	= toEvaluate.getNumberOfArguments();
 		final List<String>	result				= new ArrayList<>();
 
-		if (toEvaluate.getNumberOfArguments() > 0) for (int index = 0; index < numberOfArguments; index++) {
+		if (toEvaluate.getNumberOfArguments() > 0)
+			for (var index = 0; index < numberOfArguments; index++) {
 				String textArg = null;
-			if (index < textArguments.length) textArg = textArguments[index];
+				if (index < textArguments.length)
+					textArg = textArguments[index];
+
 				// Set the argument at position index to the current argument of the text, if it
 				// is present. Otherwise the default for that argument will be taken if present.
 				// In the worst case, an empty String will be used.
-			result.add(!(textArg == null) && !textArg.isBlank() ? textArg : index < defaults.size() ? defaults.get(index) : "");
+				result.add(!(textArg == null) && !textArg.isBlank() ? textArg
+					: index < defaults.size() ? defaults.get(index) : "");
 			}
 		return result;
 	}
@@ -257,4 +327,10 @@ public final class SystemCommandMap {
 	 * @since Envoy Client v0.2-beta
 	 */
 	public Map<String, SystemCommand> getSystemCommands() { return systemCommands; }
+
+	/**
+	 * @return the activator of any command in this map. Can be null.
+	 * @since Envoy Client v0.3-beta
+	 */
+	public Character getActivator() { return activator; }
 }

client/src/main/java/envoy/client/data/shortcuts/EnvoyShortcutConfig.java

@@ -0,0 +1,77 @@
+package envoy.client.data.shortcuts;
+
+import javafx.scene.input.*;
+
+import envoy.data.User.UserStatus;
+
+import envoy.client.data.Context;
+import envoy.client.helper.ShutdownHelper;
+import envoy.client.ui.SceneInfo;
+import envoy.client.util.UserUtil;
+
+/**
+ * Envoy-specific implementation of the keyboard-shortcut interaction offered by
+ * {@link GlobalKeyShortcuts}.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public class EnvoyShortcutConfig {
+
+	private EnvoyShortcutConfig() {}
+
+	/**
+	 * Supplies the default shortcuts for {@link GlobalKeyShortcuts}.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void initializeEnvoyShortcuts() {
+		final var instance = GlobalKeyShortcuts.getInstance();
+
+		// Add the option to exit with "Control" + "Q" or "Alt" + "F4" as offered by
+		// some desktop environments
+		instance.add(new KeyCodeCombination(KeyCode.Q, KeyCombination.CONTROL_DOWN),
+			ShutdownHelper::exit);
+
+		// Add the option to logout using "Control"+"Shift"+"L" if not in login scene
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.L, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			UserUtil::logout,
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to open settings scene with "Control"+"S", if not in login scene
+		instance.addForNotExcluded(new KeyCodeCombination(KeyCode.S, KeyCombination.CONTROL_DOWN),
+			() -> Context.getInstance().getSceneContext().load(SceneInfo.SETTINGS_SCENE),
+			SceneInfo.SETTINGS_SCENE,
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to change to status away
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.A, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			() -> UserUtil.changeStatus(UserStatus.AWAY),
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to change to status busy
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.B, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			() -> UserUtil.changeStatus(UserStatus.BUSY),
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to change to status offline
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.F, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			() -> UserUtil.changeStatus(UserStatus.OFFLINE),
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to change to status online
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.N, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			() -> UserUtil.changeStatus(UserStatus.ONLINE),
+			SceneInfo.LOGIN_SCENE);
+	}
+}

client/src/main/java/envoy/client/data/shortcuts/GlobalKeyShortcuts.java

@@ -0,0 +1,79 @@
+package envoy.client.data.shortcuts;
+
+import java.util.*;
+
+import javafx.scene.input.KeyCombination;
+
+import envoy.client.ui.SceneInfo;
+
+/**
+ * Contains all keyboard shortcuts used throughout the application.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public final class GlobalKeyShortcuts {
+
+	private final EnumMap<SceneInfo, Map<KeyCombination, Runnable>> shortcuts =
+		new EnumMap<>(SceneInfo.class);
+
+	private static GlobalKeyShortcuts instance = new GlobalKeyShortcuts();
+
+	private GlobalKeyShortcuts() {
+		for (final var sceneInfo : SceneInfo.values())
+			shortcuts.put(sceneInfo, new HashMap<KeyCombination, Runnable>());
+	}
+
+	/**
+	 * @return the instance of global keyboard shortcuts.
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static GlobalKeyShortcuts getInstance() { return instance; }
+
+	/**
+	 * Adds the given keyboard shortcut and its action to all scenes.
+	 *
+	 * @param keys   the keys to press to perform the given action
+	 * @param action the action to perform
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void add(KeyCombination keys, Runnable action) {
+		shortcuts.values().forEach(collection -> collection.put(keys, action));
+	}
+
+	/**
+	 * Adds the given keyboard shortcut and its action to all scenes that are not part of exclude.
+	 *
+	 * @param keys    the keys to press to perform the given action
+	 * @param action  the action to perform
+	 * @param exclude the scenes that should be excluded from receiving this keyboard shortcut
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void addForNotExcluded(KeyCombination keys, Runnable action, SceneInfo... exclude) {
+
+		// Computing the remaining sceneInfos
+		final var	include	= new SceneInfo[SceneInfo.values().length - exclude.length];
+		int			index	= 0;
+		outer: for (final var sceneInfo : SceneInfo.values()) {
+			for (final var excluded : exclude)
+				if (sceneInfo.equals(excluded))
+					continue outer;
+			include[index++] = sceneInfo;
+		}
+
+		// Adding the action to the remaining sceneInfos
+		for (final var sceneInfo : include)
+			shortcuts.get(sceneInfo).put(keys, action);
+	}
+
+	/**
+	 * Returns all stored keyboard shortcuts for the given scene constant.
+	 *
+	 * @param sceneInfo the currently loading scene
+	 * @return all stored keyboard shortcuts for this scene
+	 * @since Envoy Client v0.3-beta
+	 */
+	public Map<KeyCombination, Runnable> getKeyboardShortcuts(SceneInfo sceneInfo) {
+		return shortcuts.get(sceneInfo);
+	}
+}

client/src/main/java/envoy/client/data/shortcuts/KeyboardMapping.java

@@ -0,0 +1,24 @@
+package envoy.client.data.shortcuts;
+
+import java.util.Map;
+
+import javafx.scene.input.KeyCombination;
+
+import envoy.client.ui.SceneContext;
+
+/**
+ * Provides methods to set the keyboard shortcuts for a specific scene. Should only be implemented
+ * by controllers of scenes so that these methods can automatically be called inside
+ * {@link SceneContext} as soon as the underlying FXML file has been loaded.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public interface KeyboardMapping {
+
+	/**
+	 * @return all keyboard shortcuts of a scene
+	 * @since Envoy Client v0.3-beta
+	 */
+	Map<KeyCombination, Runnable> getKeyboardShortcuts();
+}

client/src/main/java/envoy/client/data/shortcuts/package-info.java

@@ -0,0 +1,7 @@
+/**
+ * Contains the necessary classes to enable using keyboard shortcuts in Envoy.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+package envoy.client.data.shortcuts;

client/src/main/java/envoy/client/event/AccountDeletion.java

@@ -0,0 +1,22 @@
+package envoy.client.event;
+
+import envoy.event.Event;
+
+/**
+ * Signifies the deletion of an account.
+ * 
+ * @author Leon Hofmeister
+ * @since Envoy Common v0.3-beta
+ */
+public class AccountDeletion extends Event<Long> {
+
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * @param value the ID of the contact that was deleted
+	 * @since Envoy Common v0.3-beta
+	 */
+	public AccountDeletion(Long value) {
+		super(value);
+	}
+}

client/src/main/java/envoy/client/event/ContactDisabled.java

@@ -0,0 +1,23 @@
+package envoy.client.event;
+
+import envoy.data.Contact;
+import envoy.event.Event;
+
+/**
+ * Signifies that the chat of a contact should be disabled.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public class ContactDisabled extends Event<Contact> {
+
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * @param contact the contact that should be disabled
+	 * @since Envoy Client v0.3-beta
+	 */
+	public ContactDisabled(Contact contact) {
+		super(contact);
+	}
+}

client/src/main/java/envoy/client/event/EnvoyCloseEvent.java

@@ -3,9 +3,8 @@ package envoy.client.event;
 import envoy.event.Event.Valueless;
 
 /**
- * This event notifies various Envoy components of the application being about
- * to shut down. This allows the graceful closing of connections, persisting
- * local data etc.
+ * This event notifies various Envoy components of the application being about to shut down. This
+ * allows the graceful closing of connections, persisting local data etc.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta

client/src/main/java/envoy/client/event/MessageDeletion.java

@@ -0,0 +1,22 @@
+package envoy.client.event;
+
+import envoy.event.Event;
+
+/**
+ * Conveys the deletion of a message.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Common v0.3-beta
+ */
+public class MessageDeletion extends Event<Long> {
+
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * @param messageID the ID of the deleted message
+	 * @since Envoy Common v0.3-beta
+	 */
+	public MessageDeletion(long messageID) {
+		super(messageID);
+	}
+}

client/src/main/java/envoy/client/event/OwnStatusChange.java

@@ -0,0 +1,23 @@
+package envoy.client.event;
+
+import envoy.data.User.UserStatus;
+import envoy.event.Event;
+
+/**
+ * Signifies a manual status change of the client user.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public class OwnStatusChange extends Event<UserStatus> {
+
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * @param value the new user status of the client user
+	 * @since Envoy Client v0.3-beta
+	 */
+	public OwnStatusChange(UserStatus value) {
+		super(value);
+	}
+}

client/src/main/java/envoy/client/helper/AlertHelper.java

@@ -15,22 +15,19 @@ public final class AlertHelper {
 	private AlertHelper() {}
 
 	/**
-	 * Asks for a confirmation dialog if {@link Settings#isAskForConfirmation()}
-	 * returns {@code true}.
-	 * Immediately executes the action if no dialog was requested or the dialog was
-	 * exited with a confirmation.
-	 * Does nothing if the dialog was closed without clicking on OK.
+	 * Asks for a confirmation dialog if {@link Settings#isAskForConfirmation()} returns
+	 * {@code true}. Immediately executes the action if no dialog was requested or the dialog was
+	 * exited with a confirmation. Does nothing if the dialog was closed without clicking on OK.
 	 *
-	 * @param alert  the (customized) alert to show. <strong>Should not be shown
-	 *               already</strong>
+	 * @param alert  the (customized) alert to show. <strong>Should not be shown already</strong>
 	 * @param action the action to perform in case of success
 	 * @since Envoy Client v0.2-beta
 	 */
 	public static void confirmAction(Alert alert, Runnable action) {
-		alert.setHeight(225);
-		alert.setWidth(400);
 		alert.setHeaderText("");
-		if (Settings.getInstance().isAskForConfirmation()) alert.showAndWait().filter(ButtonType.OK::equals).ifPresent(bu -> action.run());
-		else action.run();
+		if (Settings.getInstance().isAskForConfirmation())
+			alert.showAndWait().filter(ButtonType.OK::equals).ifPresent(bu -> action.run());
+		else
+			action.run();
 	}
 }

client/src/main/java/envoy/client/helper/ShutdownHelper.java

@@ -1,16 +1,10 @@
 package envoy.client.helper;
 
-import java.util.logging.Level;
-
-import javafx.scene.control.Alert;
-import javafx.scene.control.Alert.AlertType;
+import dev.kske.eventbus.core.EventBus;
 
 import envoy.client.data.*;
-import envoy.client.event.*;
-import envoy.client.ui.SceneContext.SceneInfo;
-import envoy.util.EnvoyLog;
-
-import dev.kske.eventbus.EventBus;
+import envoy.client.event.EnvoyCloseEvent;
+import envoy.client.ui.StatusTrayIcon;
 
 /**
  * Simplifies shutdown actions.
@@ -24,34 +18,28 @@ public final class ShutdownHelper {
 
 	/**
 	 * Exits Envoy or minimizes it, depending on the current state of
-	 * {@link Settings#isHideOnClose()}.
+	 * {@link Settings#isHideOnClose()} and {@link StatusTrayIcon#isSupported()}.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
 	public static void exit() {
-		if (Settings.getInstance().isHideOnClose()) Context.getInstance().getStage().setIconified(true);
+		exit(false);
+	}
+
+	/**
+	 * Exits Envoy immediately if {@code force = true}, else it can exit or minimize Envoy,
+	 * depending on the current state of {@link Settings#isHideOnClose()} and
+	 * {@link StatusTrayIcon#isSupported()}.
+	 *
+	 * @param force whether to close in any case.
+	 * @since Envoy Client v0.2-beta
+	 */
+	public static void exit(boolean force) {
+		if (!force && Settings.getInstance().isHideOnClose() && StatusTrayIcon.isSupported())
+			Context.getInstance().getStage().setIconified(true);
 		else {
 			EventBus.getInstance().dispatch(new EnvoyCloseEvent());
 			System.exit(0);
 		}
 	}
-
-	/**
-	 * Logs the current user out and reopens
-	 * {@link envoy.client.ui.controller.LoginScene}.
-	 *
-	 * @since Envoy Client v0.2-beta
-	 */
-	public static void logout() {
-		final var alert = new Alert(AlertType.CONFIRMATION);
-		alert.setTitle("Logout?");
-		alert.setContentText("Are you sure you want to log out?");
-
-		AlertHelper.confirmAction(alert, () -> {
-			EnvoyLog.getLogger(ShutdownHelper.class).log(Level.INFO, "A logout was requested");
-			EventBus.getInstance().dispatch(new EnvoyCloseEvent());
-			EventBus.getInstance().dispatch(new Logout());
-			Context.getInstance().getSceneContext().load(SceneInfo.LOGIN_SCENE);
-		});
-	}
 }

client/src/main/java/envoy/client/net/Client.java

@@ -5,25 +5,26 @@ import java.net.Socket;
 import java.util.concurrent.TimeoutException;
 import java.util.logging.*;
 
-import envoy.client.data.*;
-import envoy.client.event.EnvoyCloseEvent;
+import dev.kske.eventbus.core.*;
+import dev.kske.eventbus.core.Event;
+
 import envoy.data.*;
 import envoy.event.*;
 import envoy.util.*;
 
-import dev.kske.eventbus.*;
-import dev.kske.eventbus.Event;
+import envoy.client.data.ClientConfig;
+import envoy.client.event.EnvoyCloseEvent;
 
 /**
- * Establishes a connection to the server, performs a handshake and delivers
- * certain objects to the server.
+ * Establishes a connection to the server, performs a handshake and delivers certain objects to the
+ * server.
  *
  * @author Kai S. K. Engelbart
  * @author Maximilian Käfer
  * @author Leon Hofmeister
  * @since Envoy Client v0.1-alpha
  */
-public final class Client implements EventListener, Closeable {
+public final class Client implements Closeable {
 
 	// Connection handling
 	private Socket		socket;
@@ -44,26 +45,30 @@ public final class Client implements EventListener, Closeable {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Client() { eventBus.registerListener(this); }
+	public Client() {
+		eventBus.registerListener(this);
+	}
 
 	/**
-	 * Enters the online mode by acquiring a user ID from the server. As a
-	 * connection has to be established and a handshake has to be made, this method
-	 * will block for up to 5 seconds. If the handshake does exceed this time limit,
-	 * an exception is thrown.
+	 * Enters the online mode by acquiring a user ID from the server. As a connection has to be
+	 * established and a handshake has to be made, this method will block for up to 5 seconds. If
+	 * the handshake does exceed this time limit, an exception is thrown.
 	 *
 	 * @param credentials the login credentials of the user
-	 * @param cacheMap    the map of all caches needed
 	 * @throws TimeoutException     if the server could not be reached
 	 * @throws IOException          if the login credentials could not be written
-	 * @throws InterruptedException if the current thread is interrupted while
-	 *                              waiting for the handshake response
+	 * @throws InterruptedException if the current thread is interrupted while waiting for the
+	 *                              handshake response
 	 */
-	public void performHandshake(LoginCredentials credentials, CacheMap cacheMap) throws TimeoutException, IOException, InterruptedException {
-		if (online) throw new IllegalStateException("Handshake has already been performed successfully");
+	public void performHandshake(LoginCredentials credentials)
+		throws TimeoutException, IOException, InterruptedException {
+		if (online)
+			throw new IllegalStateException("Handshake has already been performed successfully");
+		rejected = false;
 
 		// Establish TCP connection
-		logger.log(Level.FINER, String.format("Attempting connection to server %s:%d...", config.getServer(), config.getPort()));
+		logger.log(Level.FINER, String.format("Attempting connection to server %s:%d...",
+			config.getServer(), config.getPort()));
 		socket = new Socket(config.getServer(), config.getPort());
 		logger.log(Level.FINE, "Successfully established TCP connection to server");
 
@@ -73,9 +78,6 @@ public final class Client implements EventListener, Closeable {
 		// Register user creation processor, contact list processor, message cache and
 		// authentication token
 		receiver.registerProcessor(User.class, sender -> this.sender = sender);
-		receiver.registerProcessors(cacheMap.getMap());
-
-		rejected = false;
 
 		// Start receiver
 		receiver.start();
@@ -95,42 +97,20 @@ public final class Client implements EventListener, Closeable {
 				return;
 			}
 
-			if (System.currentTimeMillis() - start > 5000) throw new TimeoutException("Did not log in after 5 seconds");
+			if (System.currentTimeMillis() - start > 5000) {
+				rejected = true;
+				socket.close();
+				receiver.removeAllProcessors();
+				throw new TimeoutException("Did not log in after 5 seconds");
+			}
 			Thread.sleep(500);
 		}
 
-		online = true;
-		logger.log(Level.INFO, "Handshake completed.");
-	}
-
-	/**
-	 * Initializes the {@link Receiver} used to process data sent from the server to
-	 * this client.
-	 *
-	 * @param localDB  the local database used to persist the current
-	 *                 {@link IDGenerator}
-	 * @param cacheMap the map of all caches needed
-	 * @throws IOException if no {@link IDGenerator} is present and none could be
-	 *                     requested from the server
-	 * @since Envoy Client v0.2-alpha
-	 */
-	public void initReceiver(LocalDB localDB, CacheMap cacheMap) throws IOException {
-		checkOnline();
-
-		// Remove all processors as they are only used during the handshake
+		// Remove handshake specific processors
 		receiver.removeAllProcessors();
 
-		// Relay cached messages and message status changes
-		cacheMap.get(Message.class).setProcessor(eventBus::dispatch);
-		cacheMap.get(GroupMessage.class).setProcessor(eventBus::dispatch);
-		cacheMap.get(MessageStatusChange.class).setProcessor(eventBus::dispatch);
-		cacheMap.get(GroupMessageStatusChange.class).setProcessor(eventBus::dispatch);
-
-		// Request a generator if none is present or the existing one is consumed
-		if (!localDB.hasIDGenerator() || !localDB.getIDGenerator().hasNext()) requestIDGenerator();
-
-		// Relay caches
-		cacheMap.getMap().values().forEach(Cache::relay);
+		online = true;
+		logger.log(Level.INFO, "Handshake completed.");
 	}
 
 	/**
@@ -146,14 +126,14 @@ public final class Client implements EventListener, Closeable {
 		logger.log(Level.FINE, "Sending " + obj);
 		try {
 			SerializationUtils.writeBytesWithLength(obj, socket.getOutputStream());
-		} catch (IOException e) {
+		} catch (final IOException e) {
 			throw new RuntimeException(e);
 		}
 	}
 
 	/**
-	 * Sends a message to the server. The message's status will be incremented once
-	 * it was delivered successfully.
+	 * Sends a message to the server. The message's status will be incremented once it was delivered
+	 * successfully.
 	 *
 	 * @param message the message to send
 	 * @since Envoy Client v0.3-alpha
@@ -173,11 +153,15 @@ public final class Client implements EventListener, Closeable {
 		send(new IDGeneratorRequest());
 	}
 
-	@Event(eventType = HandshakeRejection.class, priority = 1000)
-	private void onHandshakeRejection() { rejected = true; }
+	@Event(HandshakeRejection.class)
+	@Priority(1000)
+	private void onHandshakeRejection() {
+		rejected = true;
+	}
 
 	@Override
-	@Event(eventType = EnvoyCloseEvent.class, priority = 800)
+	@Event(EnvoyCloseEvent.class)
+	@Priority(50)
 	public void close() {
 		if (online) {
 			logger.log(Level.INFO, "Closing connection...");
@@ -199,7 +183,10 @@ public final class Client implements EventListener, Closeable {
 	 * @throws IllegalStateException if the client is not online
 	 * @since Envoy Client v0.3-alpha
 	 */
-	private void checkOnline() throws IllegalStateException { if (!online) throw new IllegalStateException("Client is not online"); }
+	private void checkOnline() throws IllegalStateException {
+		if (!online)
+			throw new IllegalStateException("Client is not online");
+	}
 
 	/**
 	 * @return the {@link User} as which this client is logged in

client/src/main/java/envoy/client/net/Receiver.java

@@ -6,13 +6,12 @@ import java.util.*;
 import java.util.function.Consumer;
 import java.util.logging.*;
 
+import dev.kske.eventbus.core.EventBus;
+
 import envoy.util.*;
 
-import dev.kske.eventbus.*;
-
 /**
- * Receives objects from the server and passes them to processor objects based
- * on their class.
+ * Receives objects from the server and passes them to processor objects based on their class.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.3-alpha
@@ -40,8 +39,7 @@ public final class Receiver extends Thread {
 	}
 
 	/**
-	 * Starts the receiver loop. When an object is read, it is passed to the
-	 * appropriate processor.
+	 * Starts the receiver loop. When an object is read, it is passed to the appropriate processor.
 	 *
 	 * @since Envoy Client v0.3-alpha
 	 */
@@ -66,15 +64,19 @@ public final class Receiver extends Thread {
 					// Server has stopped sending, i.e. because he went offline
 					if (bytesRead == -1) {
 						isAlive = false;
-						logger.log(Level.INFO, "Lost connection to the server. Exiting receiver...");
+						logger.log(Level.INFO,
+							"Lost connection to the server. Exiting receiver...");
 						continue;
 					}
 					logger.log(Level.WARNING,
-							String.format("LV encoding violated: expected %d bytes, received %d bytes. Discarding object...", len, bytesRead));
+						String.format(
+							"LV encoding violated: expected %d bytes, received %d bytes. Discarding object...",
+							len, bytesRead));
 					continue;
 				}
 
-				try (ObjectInputStream oin = new ObjectInputStream(new ByteArrayInputStream(objBytes))) {
+				try (ObjectInputStream oin =
+					new ObjectInputStream(new ByteArrayInputStream(objBytes))) {
 					final Object obj = oin.readObject();
 					logger.log(Level.FINE, "Received " + obj);
 
@@ -83,12 +85,19 @@ public final class Receiver extends Thread {
 					final Consumer processor = processors.get(obj.getClass());
 
 					// Dispatch to the processor if present
-					if (processor != null) processor.accept(obj);
-					// Dispatch to the event bus if the object is an event without a processor
-					else if (obj instanceof IEvent) eventBus.dispatch((IEvent) obj);
+					if (processor != null)
+						processor.accept(obj);
+					// Dispatch to the event bus if the object has no processor
+					else
+						eventBus.dispatch(obj);
+
+					// TODO: Log DeadEvent from Event Bus 1.1.0
 					// Notify if no processor could be located
-					else logger.log(Level.WARNING,
-							String.format("The received object has the %s for which no processor is defined.", obj.getClass()));
+					// else
+					// logger.log(Level.WARNING,
+					// String.format(
+					// "The received object has the %s for which no processor is defined.",
+					// obj.getClass()));
 				}
 			} catch (final SocketException | EOFException e) {
 				// Connection probably closed by client.
@@ -100,14 +109,16 @@ public final class Receiver extends Thread {
 	}
 
 	/**
-	 * Adds an object processor to this {@link Receiver}. It will be called once an
-	 * object of the accepted class has been received.
+	 * Adds an object processor to this {@link Receiver}. It will be called once an object of the
+	 * accepted class has been received.
 	 *
 	 * @param processorClass the object class accepted by the processor
 	 * @param processor      the object processor
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public <T> void registerProcessor(Class<T> processorClass, Consumer<T> processor) { processors.put(processorClass, processor); }
+	public <T> void registerProcessor(Class<T> processorClass, Consumer<T> processor) {
+		processors.put(processorClass, processor);
+	}
 
 	/**
 	 * Adds a map of object processors to this {@link Receiver}.
@@ -115,12 +126,16 @@ public final class Receiver extends Thread {
 	 * @param processors the processors to add the processors to add
 	 * @since Envoy Client v0.1-beta
 	 */
-	public void registerProcessors(Map<Class<?>, ? extends Consumer<?>> processors) { this.processors.putAll(processors); }
+	public void registerProcessors(Map<Class<?>, ? extends Consumer<?>> processors) {
+		this.processors.putAll(processors);
+	}
 
 	/**
 	 * Removes all object processors registered at this {@link Receiver}.
 	 *
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public void removeAllProcessors() { processors.clear(); }
+	public void removeAllProcessors() {
+		processors.clear();
+	}
 }

client/src/main/java/envoy/client/net/WriteProxy.java

@@ -2,15 +2,15 @@ package envoy.client.net;
 
 import java.util.logging.*;
 
-import envoy.client.data.*;
 import envoy.data.Message;
 import envoy.event.MessageStatusChange;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.*;
+
 /**
- * Implements methods to send {@link Message}s and
- * {@link MessageStatusChange}s to the server or cache them inside a
- * {@link LocalDB} depending on the online status.
+ * Implements methods to send {@link Message}s and {@link MessageStatusChange}s to the server or
+ * cache them inside a {@link LocalDB} depending on the online status.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.3-alpha
@@ -23,12 +23,11 @@ public final class WriteProxy {
 	private static final Logger logger = EnvoyLog.getLogger(WriteProxy.class);
 
 	/**
-	 * Initializes a write proxy using a client and a local database. The
-	 * corresponding cache processors are injected into the caches.
+	 * Initializes a write proxy using a client and a local database. The corresponding cache
+	 * processors are injected into the caches.
 	 *
 	 * @param client  the client instance used to send messages and events if online
-	 * @param localDB the local database used to cache messages and events if
-	 *                offline
+	 * @param localDB the local database used to cache messages and events if offline
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public WriteProxy(Client client, LocalDB localDB) {
@@ -47,34 +46,39 @@ public final class WriteProxy {
 	}
 
 	/**
-	 * Sends cached {@link Message}s and {@link MessageStatusChange}s to the
-	 * server.
+	 * Sends cached {@link Message}s and {@link MessageStatusChange}s to the server.
 	 *
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public void flushCache() { localDB.getCacheMap().getMap().values().forEach(Cache::relay); }
+	public void flushCache() {
+		localDB.getCacheMap().getMap().values().forEach(Cache::relay);
+	}
 
 	/**
-	 * Delivers a message to the server if online. Otherwise the message is cached
-	 * inside the local database.
+	 * Delivers a message to the server if online. Otherwise the message is cached inside the local
+	 * database.
 	 *
 	 * @param message the message to send
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void writeMessage(Message message) {
-		if (client.isOnline()) client.sendMessage(message);
-		else localDB.getCacheMap().getApplicable(Message.class).accept(message);
+		if (client.isOnline())
+			client.sendMessage(message);
+		else
+			localDB.getCacheMap().getApplicable(Message.class).accept(message);
 	}
 
 	/**
-	 * Delivers a message status change event to the server if online. Otherwise the
-	 * event is cached inside the local database.
+	 * Delivers a message status change event to the server if online. Otherwise the event is cached
+	 * inside the local database.
 	 *
 	 * @param evt the event to send
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void writeMessageStatusChange(MessageStatusChange evt) {
-		if (client.isOnline()) client.send(evt);
-		else localDB.getCacheMap().getApplicable(MessageStatusChange.class).accept(evt);
+		if (client.isOnline())
+			client.send(evt);
+		else
+			localDB.getCacheMap().getApplicable(MessageStatusChange.class).accept(evt);
 	}
 }

client/src/main/java/envoy/client/ui/Restorable.java

@@ -1,8 +1,8 @@
 package envoy.client.ui;
 
 /**
- * This interface defines an action that should be performed when a scene gets
- * restored from the scene stack in {@link SceneContext}.
+ * This interface defines an action that should be performed when a scene gets restored from the
+ * scene stack in {@link SceneContext}.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.1-beta
@@ -12,8 +12,7 @@ public interface Restorable {
 
 	/**
 	 * This method is getting called when a scene gets restored.<br>
-	 * Hence, it can contain anything that should be done when the underlying scene
-	 * gets restored.
+	 * Hence, it can contain anything that should be done when the underlying scene gets restored.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */

client/src/main/java/envoy/client/ui/SceneContext.java

@@ -4,75 +4,34 @@ import java.io.IOException;
 import java.util.Stack;
 import java.util.logging.Level;
 
-import javafx.application.Platform;
 import javafx.fxml.FXMLLoader;
 import javafx.scene.*;
-import javafx.scene.input.*;
 import javafx.stage.Stage;
 
-import envoy.client.data.Settings;
-import envoy.client.event.*;
-import envoy.client.helper.ShutdownHelper;
+import dev.kske.eventbus.core.*;
+
 import envoy.util.EnvoyLog;
 
-import dev.kske.eventbus.*;
+import envoy.client.data.Settings;
+import envoy.client.data.shortcuts.*;
+import envoy.client.event.*;
 
 /**
- * Manages a stack of scenes. The most recently added scene is displayed inside
- * a stage. When a scene is removed from the stack, its predecessor is
- * displayed.
+ * Manages a stack of scenes. The most recently added scene is displayed inside a stage. When a
+ * scene is removed from the stack, its predecessor is displayed.
  * <p>
- * When a scene is loaded, the style sheet for the current theme is applied to
- * it.
+ * When a scene is loaded, the style sheet for the current theme is applied to it.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
  */
-public final class SceneContext implements EventListener {
-
-	/**
-	 * Contains information about different scenes and their FXML resource files.
-	 *
-	 * @author Kai S. K. Engelbart
-	 * @since Envoy Client v0.1-beta
-	 */
-	public enum SceneInfo {
-
-		/**
-		 * The main scene in which the chat screen is displayed.
-		 *
-		 * @since Envoy Client v0.1-beta
-		 */
-		CHAT_SCENE("/fxml/ChatScene.fxml"),
-
-		/**
-		 * The scene in which the settings screen is displayed.
-		 *
-		 * @since Envoy Client v0.1-beta
-		 */
-		SETTINGS_SCENE("/fxml/SettingsScene.fxml"),
-
-		/**
-		 * The scene in which the login screen is displayed.
-		 *
-		 * @since Envoy Client v0.1-beta
-		 */
-		LOGIN_SCENE("/fxml/LoginScene.fxml");
-
-		/**
-		 * The path to the FXML resource.
-		 */
-		public final String path;
-
-		SceneInfo(String path) { this.path = path; }
-	}
+public final class SceneContext {
 
 	private final Stage			stage;
-	private final FXMLLoader	loader			= new FXMLLoader();
-	private final Stack<Scene>	sceneStack		= new Stack<>();
-	private final Stack<Object>	controllerStack	= new Stack<>();
+	private final Stack<Parent>	roots		= new Stack<>();
+	private final Stack<Object>	controllers	= new Stack<>();
 
-	private static final Settings settings = Settings.getInstance();
+	private Scene scene;
 
 	/**
 	 * Initializes the scene context.
@@ -88,44 +47,44 @@ public final class SceneContext implements EventListener {
 	/**
 	 * Loads a new scene specified by a scene info.
 	 *
-	 * @param sceneInfo specifies the scene to load
+	 * @param info specifies the scene to load
 	 * @throws RuntimeException if the loading process fails
 	 * @since Envoy Client v0.1-beta
 	 */
-	public void load(SceneInfo sceneInfo) {
-		EnvoyLog.getLogger(SceneContext.class).log(Level.FINER, "Loading scene " + sceneInfo);
-		loader.setRoot(null);
-		loader.setController(null);
+	public void load(SceneInfo info) {
+		EnvoyLog.getLogger(SceneContext.class).log(Level.FINER, "Loading scene " + info);
 
 		try {
-			final var	rootNode	= (Parent) loader.load(getClass().getResourceAsStream(sceneInfo.path));
-			final var	scene		= new Scene(rootNode);
-			controllerStack.push(loader.getController());
 
-			sceneStack.push(scene);
-			stage.setScene(scene);
+			// Load root node and controller
+			var		loader		= new FXMLLoader();
+			Parent	root		= loader.load(getClass().getResourceAsStream(info.path));
+			Object	controller	= loader.getController();
+			roots.push(root);
+			controllers.push(controller);
 
-			// Add the option to exit Linux-like with "Control" + "Q"
-			scene.getAccelerators().put(new KeyCodeCombination(KeyCode.Q, KeyCombination.CONTROL_DOWN), ShutdownHelper::exit);
+			if (scene == null) {
 
-			// Add the option to logout using "Control"+"Shift"+"L" if not in login scene
-			if (sceneInfo != SceneInfo.LOGIN_SCENE) scene.getAccelerators()
-				.put(new KeyCodeCombination(KeyCode.L, KeyCombination.CONTROL_DOWN, KeyCombination.SHIFT_DOWN), ShutdownHelper::logout);
-
-			// Add the option to open the settings scene with "Control"+"S", if being in
-			// chat scene
-			if (sceneInfo.equals(SceneInfo.CHAT_SCENE))
-				scene.getAccelerators().put(new KeyCodeCombination(KeyCode.S, KeyCombination.CONTROL_DOWN), () -> load(SceneInfo.SETTINGS_SCENE));
-
-			// The LoginScene is the only scene not intended to be resized
-			// As strange as it seems, this is needed as otherwise the LoginScene won't be
-			// displayed on some OS (...Debian...)
-			stage.sizeToScene();
-			Platform.runLater(() -> stage.setResizable(sceneInfo != SceneInfo.LOGIN_SCENE));
+				// One-time scene initialization
+				scene = new Scene(root, stage.getWidth(), stage.getHeight());
 				applyCSS();
-			stage.show();
-		} catch (final IOException e) {
-			EnvoyLog.getLogger(SceneContext.class).log(Level.SEVERE, String.format("Could not load scene for %s: ", sceneInfo), e);
+				stage.setScene(scene);
+			} else {
+				scene.setRoot(root);
+			}
+
+			// Remove previous keyboard shortcuts
+			scene.getAccelerators().clear();
+
+			// Supply the global custom keyboard shortcuts for that scene
+			scene.getAccelerators()
+				.putAll(GlobalKeyShortcuts.getInstance().getKeyboardShortcuts(info));
+
+			// Supply the scene specific keyboard shortcuts
+			if (controller instanceof KeyboardMapping)
+				scene.getAccelerators()
+					.putAll(((KeyboardMapping) controller).getKeyboardShortcuts());
+		} catch (IOException e) {
 			throw new RuntimeException(e);
 		}
 	}
@@ -137,48 +96,55 @@ public final class SceneContext implements EventListener {
 	 */
 	public void pop() {
 
-		// Pop scene and controller
-		sceneStack.pop();
-		controllerStack.pop();
+		// Pop current root node and controller
+		roots.pop();
+		controllers.pop();
 
 		// Apply new scene if present
-		if (!sceneStack.isEmpty()) {
-			final var newScene = sceneStack.peek();
-			stage.setScene(newScene);
-			applyCSS();
-			stage.sizeToScene();
-			// If the controller implements the Restorable interface,
-			// the actions to perform on restoration will be executed here
-			final var controller = controllerStack.peek();
-			if (controller instanceof Restorable) ((Restorable) controller).onRestore();
+		if (!roots.isEmpty()) {
+			scene.setRoot(roots.peek());
+
+			// Invoke restore if controller is restorable
+			var controller = controllers.peek();
+			if (controller instanceof Restorable)
+				((Restorable) controller).onRestore();
+		} else {
+
+			// Remove the current scene entirely
+			scene = null;
+			stage.setScene(null);
 		}
-		stage.show();
 	}
 
 	private void applyCSS() {
-		if (!sceneStack.isEmpty()) {
-			final var	styleSheets	= stage.getScene().getStylesheets();
-			final var	themeCSS	= "/css/" + settings.getCurrentTheme() + ".css";
+		if (scene != null) {
+			var	styleSheets	= scene.getStylesheets();
+			var	themeCSS	= "/css/" + Settings.getInstance().getCurrentTheme() + ".css";
 			styleSheets.clear();
-			styleSheets.addAll(getClass().getResource("/css/base.css").toExternalForm(), getClass().getResource(themeCSS).toExternalForm());
+			styleSheets.addAll(getClass().getResource("/css/base.css").toExternalForm(),
+				getClass().getResource(themeCSS).toExternalForm());
 		}
 	}
 
-	@Event(eventType = Logout.class, priority = 150)
+	@Event(Logout.class)
+	@Priority(150)
 	private void onLogout() {
-		sceneStack.clear();
-		controllerStack.clear();
+		roots.clear();
+		controllers.clear();
 	}
 
-	@Event(priority = 150, eventType = ThemeChangeEvent.class)
-	private void onThemeChange() { applyCSS(); }
+	@Event(ThemeChangeEvent.class)
+	@Priority(150)
+	private void onThemeChange() {
+		applyCSS();
+	}
 
 	/**
 	 * @param <T> the type of the controller
 	 * @return the controller used by the current scene
 	 * @since Envoy Client v0.1-beta
 	 */
-	public <T> T getController() { return (T) controllerStack.peek(); }
+	public <T> T getController() { return (T) controllers.peek(); }
 
 	/**
 	 * @return the stage in which the scenes are displayed
@@ -190,5 +156,5 @@ public final class SceneContext implements EventListener {
 	 * @return whether the scene stack is empty
 	 * @since Envoy Client v0.2-beta
 	 */
-	public boolean isEmpty() { return sceneStack.isEmpty(); }
+	public boolean isEmpty() { return roots.isEmpty(); }
 }

client/src/main/java/envoy/client/ui/SceneInfo.java

@@ -0,0 +1,40 @@
+package envoy.client.ui;
+
+/**
+ * Contains information about different scenes and their FXML resource files.
+ *
+ * @author Kai S. K. Engelbart
+ * @since Envoy Client v0.1-beta
+ */
+public enum SceneInfo {
+
+	/**
+	 * The main scene in which the chat screen is displayed.
+	 *
+	 * @since Envoy Client v0.1-beta
+	 */
+	CHAT_SCENE("/fxml/ChatScene.fxml"),
+
+	/**
+	 * The scene in which the settings screen is displayed.
+	 *
+	 * @since Envoy Client v0.1-beta
+	 */
+	SETTINGS_SCENE("/fxml/SettingsScene.fxml"),
+
+	/**
+	 * The scene in which the login screen is displayed.
+	 *
+	 * @since Envoy Client v0.1-beta
+	 */
+	LOGIN_SCENE("/fxml/LoginScene.fxml");
+
+	/**
+	 * The path to the FXML resource.
+	 */
+	public final String path;
+
+	SceneInfo(String path) {
+		this.path = path;
+	}
+}

client/src/main/java/envoy/client/ui/Startup.java

@@ -10,18 +10,19 @@ import javafx.scene.control.Alert;
 import javafx.scene.control.Alert.AlertType;
 import javafx.stage.Stage;
 
-import envoy.client.data.*;
-import envoy.client.helper.ShutdownHelper;
-import envoy.client.net.Client;
-import envoy.client.ui.SceneContext.SceneInfo;
-import envoy.client.ui.controller.LoginScene;
-import envoy.client.util.IconUtil;
 import envoy.data.*;
 import envoy.data.User.UserStatus;
-import envoy.event.*;
+import envoy.event.UserStatusChange;
 import envoy.exception.EnvoyException;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.*;
+import envoy.client.data.shortcuts.EnvoyShortcutConfig;
+import envoy.client.helper.ShutdownHelper;
+import envoy.client.net.Client;
+import envoy.client.ui.controller.LoginScene;
+import envoy.client.util.IconUtil;
+
 /**
  * Handles application startup.
  *
@@ -36,7 +37,7 @@ public final class Startup extends Application {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	public static final String VERSION = "0.1-beta";
+	public static final String VERSION = "0.2-beta";
 
 	private static LocalDB localDB;
 
@@ -46,8 +47,8 @@ public final class Startup extends Application {
 	private static final Logger			logger	= EnvoyLog.getLogger(Startup.class);
 
 	/**
-	 * Loads the configuration, initializes the client and the local database and
-	 * delegates the rest of the startup process to {@link LoginScene}.
+	 * Loads the configuration, initializes the client and the local database and delegates the rest
+	 * of the startup process to {@link LoginScene}.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -56,7 +57,8 @@ public final class Startup extends Application {
 
 		// Initialize config and logger
 		try {
-			config.loadAll(Startup.class, "client.properties", getParameters().getRaw().toArray(new String[0]));
+			config.loadAll(Startup.class, "client.properties",
+				getParameters().getRaw().toArray(new String[0]));
 			EnvoyLog.initialize(config);
 		} catch (final IllegalStateException e) {
 			new Alert(AlertType.ERROR, "Error loading configuration values:\n" + e);
@@ -84,20 +86,25 @@ public final class Startup extends Application {
 		stage.setTitle("Envoy");
 		stage.getIcons().add(IconUtil.loadIcon("envoy_logo"));
 
+		// Configure global shortcuts
+		EnvoyShortcutConfig.initializeEnvoyShortcuts();
+
 		// Create scene context
 		final var sceneContext = new SceneContext(stage);
 		context.setSceneContext(sceneContext);
 
-		// Authenticate with token if present
+		// Authenticate with token if present or load login scene
 		if (localDB.getAuthToken() != null) {
 			logger.info("Attempting authentication with token...");
 			localDB.loadUserData();
 			if (!performHandshake(
-					LoginCredentials.loginWithToken(localDB.getUser().getName(), localDB.getAuthToken(), VERSION, localDB.getLastSync())))
+				LoginCredentials.loginWithToken(localDB.getUser().getName(), localDB.getAuthToken(),
+					VERSION, localDB.getLastSync())))
 				sceneContext.load(SceneInfo.LOGIN_SCENE);
 		} else
-			// Load login scene
 			sceneContext.load(SceneInfo.LOGIN_SCENE);
+
+		stage.show();
 	}
 
 	/**
@@ -108,18 +115,23 @@ public final class Startup extends Application {
 	 * @since Envoy Client v0.2-beta
 	 */
 	public static boolean performHandshake(LoginCredentials credentials) {
-		final var cacheMap = new CacheMap();
-		cacheMap.put(Message.class, new Cache<Message>());
-		cacheMap.put(GroupMessage.class, new Cache<GroupMessage>());
-		cacheMap.put(MessageStatusChange.class, new Cache<MessageStatusChange>());
-		cacheMap.put(GroupMessageStatusChange.class, new Cache<GroupMessageStatusChange>());
+		final var originalStatus =
+			localDB.getUser() == null ? UserStatus.ONLINE : localDB.getUser().getStatus();
 		try {
-			client.performHandshake(credentials, cacheMap);
+			client.performHandshake(credentials);
 			if (client.isOnline()) {
+
+				// Restore the original status as the server automatically returns status ONLINE
+				client.getSender().setStatus(originalStatus);
 				loadChatScene();
-				client.initReceiver(localDB, cacheMap);
+
+				// Request an ID generator if none is present or the existing one is consumed
+				if (!localDB.hasIDGenerator() || !localDB.getIDGenerator().hasNext())
+					client.requestIDGenerator();
+
 				return true;
-			} else return false;
+			} else
+				return false;
 		} catch (IOException | InterruptedException | TimeoutException e) {
 			logger.log(Level.INFO, "Could not connect to server. Entering offline mode...");
 			return attemptOfflineMode(credentials.getIdentifier());
@@ -127,8 +139,8 @@ public final class Startup extends Application {
 	}
 
 	/**
-	 * Attempts to load {@link envoy.client.ui.controller.ChatScene} in offline mode
-	 * for a given user.
+	 * Attempts to load {@link envoy.client.ui.controller.ChatScene} in offline mode for a given
+	 * user.
 	 *
 	 * @param identifier the identifier of the user - currently his username
 	 * @return whether the offline mode could be entered
@@ -138,7 +150,8 @@ public final class Startup extends Application {
 		try {
 			// Try entering offline mode
 			final User clientUser = localDB.getUsers().get(identifier);
-			if (clientUser == null) throw new EnvoyException("Could not enter offline mode: user name unknown");
+			if (clientUser == null)
+				throw new EnvoyException("Could not enter offline mode: user name unknown");
 			client.setSender(clientUser);
 			loadChatScene();
 			return true;
@@ -170,7 +183,8 @@ public final class Startup extends Application {
 	private static void loadChatScene() {
 
 		// Set client user in local database
-		localDB.setUser(client.getSender());
+		final var user = client.getSender();
+		localDB.setUser(user);
 
 		// Initialize chats in local database
 		try {
@@ -178,14 +192,22 @@ public final class Startup extends Application {
 		} catch (final FileNotFoundException e) {
 			// The local database file has not yet been created, probably first login
 		} catch (final Exception e) {
-			new Alert(AlertType.ERROR, "Error while loading local database: " + e + "\nChats will not be stored locally.").showAndWait();
+			new Alert(AlertType.ERROR,
+				"Error while loading local database: " + e + "\nChats will not be stored locally.")
+					.showAndWait();
 			logger.log(Level.WARNING, "Could not load local database: ", e);
 		}
 
 		context.initWriteProxy();
 
-		if (client.isOnline()) context.getWriteProxy().flushCache();
-		else
+		if (client.isOnline()) {
+			context.getWriteProxy().flushCache();
+
+			// Inform the server that this user has a different user status than expected
+			if (!user.getStatus().equals(UserStatus.ONLINE))
+				client.send(new UserStatusChange(user));
+		} else
+
 			// Set all contacts to offline mode
 			localDB.getChats()
 				.stream()
@@ -197,26 +219,26 @@ public final class Startup extends Application {
 		final var stage = context.getStage();
 
 		// Pop LoginScene if present
-		if (!context.getSceneContext().isEmpty()) context.getSceneContext().pop();
+		if (!context.getSceneContext().isEmpty())
+			context.getSceneContext().pop();
 
 		// Load ChatScene
 		stage.setMinHeight(400);
 		stage.setMinWidth(843);
-		context.getSceneContext().load(SceneContext.SceneInfo.CHAT_SCENE);
+		context.getSceneContext().load(SceneInfo.CHAT_SCENE);
 		stage.centerOnScreen();
 
-		if (StatusTrayIcon.isSupported()) {
-
 		// Exit or minimize the stage when a close request occurs
-			stage.setOnCloseRequest(e -> { ShutdownHelper.exit(); if (Settings.getInstance().isHideOnClose()) e.consume(); });
+		stage.setOnCloseRequest(
+			e -> {
+				ShutdownHelper.exit();
+				if (Settings.getInstance().isHideOnClose() && StatusTrayIcon.isSupported())
+					e.consume();
+			});
 
 		// Initialize status tray icon
-			final var trayIcon = new StatusTrayIcon(stage);
-			Settings.getInstance().getItems().get("hideOnClose").setChangeHandler(c -> {
-				if ((Boolean) c) trayIcon.show();
-				else trayIcon.hide();
-			});
-		}
+		if (StatusTrayIcon.isSupported())
+			new StatusTrayIcon(stage).show();
 
 		// Start auto save thread
 		localDB.initAutoSave();

client/src/main/java/envoy/client/ui/StatusTrayIcon.java

@@ -1,36 +1,62 @@
 package envoy.client.ui;
 
+import static java.awt.Image.SCALE_SMOOTH;
+
 import java.awt.*;
 import java.awt.TrayIcon.MessageType;
+import java.awt.image.BufferedImage;
 
 import javafx.application.Platform;
 import javafx.stage.Stage;
 
-import envoy.client.helper.ShutdownHelper;
-import envoy.client.util.IconUtil;
-import envoy.data.Message;
+import dev.kske.eventbus.core.Event;
+import dev.kske.eventbus.core.EventBus;
 
-import dev.kske.eventbus.*;
-import dev.kske.eventbus.Event;
+import envoy.data.Message;
+import envoy.data.User.UserStatus;
+
+import envoy.client.data.*;
+import envoy.client.event.*;
+import envoy.client.helper.ShutdownHelper;
+import envoy.client.util.*;
 
 /**
+ * A tray icon with the Envoy logo, an "Envoy" tool tip and a pop-up menu with menu items for
+ * <ul>
+ * <li>Changing the user status</li>
+ * <li>Logging out</li>
+ * <li>Quitting Envoy</li>
+ * </ul>
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.2-alpha
  */
-public final class StatusTrayIcon implements EventListener {
+public final class StatusTrayIcon {
 
 	/**
-	 * The {@link TrayIcon} provided by the System Tray API for controlling the
-	 * system tray. This includes displaying the icon, but also creating
-	 * notifications when new messages are received.
+	 * The {@link TrayIcon} provided by the System Tray API for controlling the system tray. This
+	 * includes displaying the icon, but also creating notifications when new messages are received.
 	 */
 	private final TrayIcon trayIcon;
 
 	/**
-	 * A received {@link Message} is only displayed as a system tray notification if
-	 * this variable is set to {@code true}.
+	 * A received {@link Message} is only displayed as a system tray notification if this variable
+	 * is set to {@code true}.
 	 */
-	private boolean displayMessages;
+	private boolean displayMessageNotification;
+
+	/**
+	 * The size of the tray icon's image.
+	 */
+	private final Dimension size;
+
+	/**
+	 * The Envoy logo on which the current user status and unread message count will be drawn to
+	 * compose the tray icon.
+	 */
+	private final Image logo;
+
+	private static final Font unreadMessageFont = new Font("sans-serif", Font.PLAIN, 8);
 
 	/**
 	 * @return {@code true} if the status tray icon is supported on this platform
@@ -39,31 +65,56 @@ public final class StatusTrayIcon implements EventListener {
 	public static boolean isSupported() { return SystemTray.isSupported(); }
 
 	/**
-	 * Creates a {@link StatusTrayIcon} with the Envoy logo, a tool tip and a pop-up
-	 * menu.
+	 * Creates a {@link StatusTrayIcon} with the Envoy logo, a tool tip and a pop-up menu.
 	 *
-	 * @param stage the stage whose focus determines if message
-	 *              notifications are displayed
+	 * @param stage the stage whose focus determines if message notifications are displayed
 	 * @since Envoy Client v0.2-beta
 	 */
 	public StatusTrayIcon(Stage stage) {
-		trayIcon = new TrayIcon(IconUtil.loadAWTCompatible("/icons/envoy_logo.png"), "Envoy");
-		trayIcon.setImageAutoSize(true);
-		trayIcon.setToolTip("You are notified if you have unread messages.");
+		size	= SystemTray.getSystemTray().getTrayIconSize();
+		logo	= IconUtil.loadAWTCompatible("/icons/envoy_logo.png").getScaledInstance(size.width,
+			size.height, SCALE_SMOOTH);
 
-		final PopupMenu popup = new PopupMenu();
+		final var popup = new PopupMenu();
 
-		final MenuItem exitMenuItem = new MenuItem("Exit");
-		exitMenuItem.addActionListener(evt -> ShutdownHelper.exit());
+		// Adding the exit menu item
+		final var exitMenuItem = new MenuItem("Exit");
+		exitMenuItem.addActionListener(evt -> ShutdownHelper.exit(true));
 		popup.add(exitMenuItem);
 
-		trayIcon.setPopupMenu(popup);
+		// Adding the logout menu item
+		final var logoutMenuItem = new MenuItem("Logout");
+		logoutMenuItem.addActionListener(evt -> Platform.runLater(UserUtil::logout));
+		popup.add(logoutMenuItem);
 
-		// Only display messages if the stage is not focused
-		stage.focusedProperty().addListener((ov, onHidden, onShown) -> displayMessages = !ov.getValue());
+		// Adding the status change items
+		final var statusSubMenu = new Menu("Change status");
+		for (final var status : UserStatus.values()) {
+			final var statusMenuItem = new MenuItem(status.toString().toLowerCase());
+			statusMenuItem
+				.addActionListener(evt -> Platform.runLater(() -> UserUtil.changeStatus(status)));
+			statusSubMenu.add(statusMenuItem);
+		}
+		popup.add(statusSubMenu);
+
+		// Initialize the icon
+		trayIcon = new TrayIcon(createImage(), "Envoy", popup);
+
+		// Only display messages if the stage is not focused and the current user status
+		// is not BUSY (if BUSY, displayMessageNotification will be false)
+		stage.focusedProperty()
+			.addListener((ov, wasFocused, isFocused) -> displayMessageNotification =
+				!displayMessageNotification && wasFocused ? false : !isFocused);
+
+		// Listen to changes in the total unread message amount
+		Chat.getTotalUnreadAmount().addListener((ov, oldValue, newValue) -> updateImage());
 
 		// Show the window if the user clicks on the icon
-		trayIcon.addActionListener(evt -> Platform.runLater(() -> { stage.setIconified(false); stage.toFront(); stage.requestFocus(); }));
+		trayIcon.addActionListener(evt -> Platform.runLater(() -> {
+			stage.setIconified(false);
+			stage.toFront();
+			stage.requestFocus();
+		}));
 
 		// Start processing message events
 		EventBus.getInstance().registerListener(this);
@@ -77,7 +128,7 @@ public final class StatusTrayIcon implements EventListener {
 	public void show() {
 		try {
 			SystemTray.getSystemTray().add(trayIcon);
-		} catch (final AWTException e) {}
+		} catch (AWTException e) {}
 	}
 
 	/**
@@ -85,13 +136,89 @@ public final class StatusTrayIcon implements EventListener {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public void hide() { SystemTray.getSystemTray().remove(trayIcon); }
+	@Event(Logout.class)
+	public void hide() {
+		SystemTray.getSystemTray().remove(trayIcon);
+	}
+
+	@Event
+	private void onOwnStatusChange(OwnStatusChange statusChange) {
+		displayMessageNotification = !statusChange.get().equals(UserStatus.BUSY);
+		trayIcon.getImage().flush();
+		trayIcon.setImage(createImage());
+	}
 
 	@Event
 	private void onMessage(Message message) {
-		if (displayMessages) trayIcon.displayMessage(
-				message.hasAttachment() ? "New " + message.getAttachment().getType().toString().toLowerCase() + " message received" : "New message received",
-				message.getText(),
-				MessageType.INFO);
+		if (displayMessageNotification)
+			trayIcon
+				.displayMessage(message.hasAttachment()
+					? "New " + message.getAttachment().getType().toString().toLowerCase()
+						+ " message received"
+					: "New message received", message.getText(), MessageType.INFO);
+	}
+
+	/**
+	 * Updates the tray icon's image by first releasing the resources held by the current image and
+	 * then setting a new one generated by the {@link StatusTrayIcon#createImage()} method.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	private void updateImage() {
+		trayIcon.getImage().flush();
+		trayIcon.setImage(createImage());
+	}
+
+	/**
+	 * Composes an icon that displays the current user status and the amount of unread messages, if
+	 * any are present.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	private BufferedImage createImage() {
+
+		// Create a new image with the dimensions of the logo
+		var img = new BufferedImage(size.width, size.height, BufferedImage.TYPE_INT_ARGB);
+
+		// Obtain the draw graphics of the image and copy the logo
+		var g = img.createGraphics();
+		g.drawImage(logo, 0, 0, null);
+
+		// Draw the current user status
+		switch (Context.getInstance().getLocalDB().getUser().getStatus()) {
+			case ONLINE:
+				g.setColor(Color.GREEN);
+				break;
+			case AWAY:
+				g.setColor(Color.ORANGE);
+				break;
+			case BUSY:
+				g.setColor(Color.RED);
+				break;
+			case OFFLINE:
+				g.setColor(Color.GRAY);
+		}
+		g.fillOval(size.width / 2, size.height / 2, size.width / 2, size.height / 2);
+
+		// Draw total amount of unread messages, if any are present
+		if (Chat.getTotalUnreadAmount().get() > 0) {
+
+			// Draw black background circle
+			g.setColor(Color.BLACK);
+			g.fillOval(size.width / 2, 0, size.width / 2, size.height / 2);
+
+			// Unread amount in white
+			String unreadAmount = Chat.getTotalUnreadAmount().get() > 9 ? "9+"
+				: String.valueOf(Chat.getTotalUnreadAmount().get());
+			g.setColor(Color.WHITE);
+			g.setFont(unreadMessageFont);
+			g.drawString(unreadAmount,
+				3 * size.width / 4 - g.getFontMetrics().stringWidth(unreadAmount) / 2,
+				size.height / 2);
+		}
+
+		// Finish drawing
+		g.dispose();
+		return img;
 	}
 }

client/src/main/java/envoy/client/ui/chatscene/ChatSceneCommands.java

@@ -0,0 +1,194 @@
+package envoy.client.ui.chatscene;
+
+import java.util.Random;
+import java.util.function.*;
+import java.util.logging.Level;
+
+import javafx.scene.control.*;
+import javafx.scene.control.Alert.AlertType;
+import javafx.scene.control.skin.VirtualFlow;
+
+import envoy.data.Message;
+import envoy.data.User.UserStatus;
+import envoy.util.EnvoyLog;
+
+import envoy.client.data.Context;
+import envoy.client.data.commands.*;
+import envoy.client.helper.ShutdownHelper;
+import envoy.client.ui.SceneInfo;
+import envoy.client.ui.controller.ChatScene;
+import envoy.client.util.*;
+
+/**
+ * Contains all {@link SystemCommand}s used for {@link envoy.client.ui.controller.ChatScene}.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public final class ChatSceneCommands {
+
+	private final ListView<Message>		messageList;
+	private final SystemCommandMap		messageTextAreaCommands	= new SystemCommandMap();
+	private final SystemCommandBuilder	builder					=
+		new SystemCommandBuilder(messageTextAreaCommands);
+
+	private static final String messageDependentCommandDescription =
+		" the given message. Use s/S to use the selected message. Otherwise expects a number relative to the uppermost completely visible message.";
+
+	/**
+	 * @param messageList the message list to use for some commands
+	 * @param chatScene   the instance of {@code ChatScene} that uses this object
+	 * @since Envoy Client v0.3-beta
+	 */
+	public ChatSceneCommands(ListView<Message> messageList, ChatScene chatScene) {
+		this.messageList = messageList;
+
+		// Error message initialization
+		builder.setAction(text -> { throw new RuntimeException(); })
+			.setDescription("Shows an error message.").buildNoArg("error");
+
+		// Do A Barrel roll initialization
+		final var random = new Random();
+		builder
+			.setAction(text -> chatScene.doABarrelRoll(Integer.parseInt(text.get(0)),
+				Double.parseDouble(text.get(1))))
+			.setDefaults(Integer.toString(random.nextInt(3) + 1),
+				Double.toString(random.nextDouble() * 3 + 1))
+			.setDescription("See for yourself :)")
+			.setNumberOfArguments(2)
+			.build("dabr");
+
+		// Logout initialization
+		builder.setAction(text -> UserUtil.logout()).setDescription("Logs you out.")
+			.buildNoArg("logout");
+
+		// Exit initialization
+		builder.setAction(text -> ShutdownHelper.exit()).setNumberOfArguments(0)
+			.setDescription("Exits the program.").build("exit", false);
+		builder.build("q");
+
+		// Open settings scene initialization
+		builder
+			.setAction(
+				text -> Context.getInstance().getSceneContext().load(SceneInfo.SETTINGS_SCENE))
+			.setDescription("Opens the settings screen")
+			.buildNoArg("settings");
+
+		// Status change initialization
+		builder.setAction(text -> {
+			try {
+				UserUtil.changeStatus(Enum.valueOf(UserStatus.class, text.get(0).toUpperCase()));
+			} catch (final IllegalArgumentException e) {
+				final var alert = new Alert(AlertType.ERROR);
+				alert.setContentText("Please provide an existing status");
+				alert.showAndWait();
+			}
+		}).setDescription("Changes your status to the given status.").setNumberOfArguments(1)
+			.setDefaults("").build("status");
+
+		// Selection of a new message initialization
+		messageDependantAction("s",
+			m -> {
+				messageList.getSelectionModel().clearSelection();
+				messageList.getSelectionModel().select(m);
+			},
+			m -> true,
+			"Selects");
+
+		// Copy text of selection initialization
+		messageDependantAction("cp", MessageUtil::copyMessageText, m -> !m.getText().isEmpty(),
+			"Copies the text of");
+
+		// Delete selection initialization
+		messageDependantAction("del", MessageUtil::deleteMessage, m -> true, "Deletes");
+
+		// Save attachment of selection initialization
+		messageDependantAction("save-att", MessageUtil::saveAttachment, Message::hasAttachment,
+			"Saves the attachment of");
+	}
+
+	private void messageDependantAction(String command, Consumer<Message> action,
+		Predicate<Message> additionalCheck, String description) {
+		builder.setAction(text -> {
+			final var positionalArgument = text.get(0).toLowerCase();
+
+			// the currently selected message was requested
+			if (positionalArgument.startsWith("s")) {
+				final var relativeString =
+					positionalArgument.length() == 1 ? "" : positionalArgument.substring(1);
+
+				// Only s has been used as input
+				if (positionalArgument.length() == 1) {
+					final var selectedMessage = messageList.getSelectionModel().getSelectedItem();
+					if (selectedMessage != null && additionalCheck.test(selectedMessage))
+						action.accept(selectedMessage);
+					return;
+
+					// Either s++ or s-- has been requested
+				} else if (relativeString.equals("++") || relativeString.equals("--"))
+					selectionNeighbor(action, additionalCheck, positionalArgument);
+
+				// A message relative to the currently selected message should be used (i.e.
+				// s+4)
+				else
+					useRelativeMessage(command, action, additionalCheck, relativeString, true);
+
+				// Either ++s or --s has been requested
+			} else if (positionalArgument.equals("--s") || positionalArgument.equals("++s"))
+				selectionNeighbor(action, additionalCheck, positionalArgument);
+
+			// Just a number is expected: ((+)4)
+			else
+				useRelativeMessage(command, action, additionalCheck, positionalArgument, false);
+		}).setDefaults("s").setNumberOfArguments(1)
+			.setDescription(description.concat(messageDependentCommandDescription)).build(command);
+	}
+
+	private void selectionNeighbor(Consumer<Message> action, Predicate<Message> additionalCheck,
+		final String positionalArgument) {
+		final var wantedIndex = messageList.getSelectionModel().getSelectedIndex()
+			+ (positionalArgument.contains("+") ? 1 : -1);
+		messageList.getSelectionModel().clearAndSelect(wantedIndex);
+		final var selectedMessage = messageList.getItems().get(wantedIndex);
+		if (selectedMessage != null && additionalCheck.test(selectedMessage))
+			action.accept(selectedMessage);
+	}
+
+	private void useRelativeMessage(String command, Consumer<Message> action,
+		Predicate<Message> additionalCheck, final String positionalArgument,
+		boolean useSelectedMessage) throws NumberFormatException {
+		final var	stripPlus	=
+			positionalArgument.startsWith("+") ? positionalArgument.substring(1)
+				: positionalArgument;
+		final var	incDec		= Integer.valueOf(stripPlus);
+		try {
+
+			// The currently selected message is the base message
+			if (useSelectedMessage) {
+				final var messageToUse = messageList.getItems()
+					.get(messageList.getSelectionModel().getSelectedIndex() + incDec);
+				if (messageToUse != null && additionalCheck.test(messageToUse))
+					action.accept(messageToUse);
+
+				// The currently upmost completely visible message is the base message
+			} else {
+				final var messageToUse = messageList.getItems()
+					.get(((VirtualFlow<?>) messageList.lookup(".virtual-flow"))
+						.getFirstVisibleCell().getIndex() + 1 + incDec);
+				if (messageToUse != null && additionalCheck.test(messageToUse))
+					action.accept(messageToUse);
+			}
+		} catch (final IndexOutOfBoundsException e) {
+			EnvoyLog.getLogger(ChatSceneCommands.class)
+				.log(Level.INFO,
+					" A non-existing message was requested by the user for System command "
+						+ command);
+		}
+	}
+
+	/**
+	 * @return the map used by this {@code ChatSceneCommands}
+	 * @since Envoy Client v0.3-beta
+	 */
+	public SystemCommandMap getChatSceneCommands() { return messageTextAreaCommands; }
+}

client/src/main/java/envoy/client/ui/chatscene/TextInputContextMenu.java

@@ -1,4 +1,4 @@
-package envoy.client.ui.control;
+package envoy.client.ui.chatscene;
 
 import java.util.function.Consumer;
 
@@ -7,8 +7,8 @@ import javafx.scene.control.*;
 import javafx.scene.input.Clipboard;
 
 /**
- * Displays a context menu that offers an additional option when one of
- * its menu items has been clicked.
+ * Displays a context menu that offers an additional option when one of its menu items has been
+ * clicked.
  * <p>
  * Current options are:
  * <ul>
@@ -24,9 +24,8 @@ import javafx.scene.input.Clipboard;
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
- * @apiNote please refrain from using
- *          {@link ContextMenu#setOnShowing(EventHandler)} as this is already
- *          used by this component
+ * @apiNote please refrain from using {@link ContextMenu#setOnShowing(EventHandler)} as this is
+ *          already used by this component
  */
 public class TextInputContextMenu extends ContextMenu {
 
@@ -38,11 +37,10 @@ public class TextInputContextMenu extends ContextMenu {
 	private final MenuItem	deleteMI	= new MenuItem("Delete selection");
 	private final MenuItem	clearMI		= new MenuItem("Clear");
 	private final MenuItem	selectAllMI	= new MenuItem("Select all");
-	private final MenuItem	separatorMI	= new SeparatorMenuItem();
 
 	/**
-	 * Creates a new {@code TextInputContextMenu} with an optional action when
-	 * this menu was clicked. Currently shows:
+	 * Creates a new {@code TextInputContextMenu} with an optional action when this menu was
+	 * clicked. Currently shows:
 	 * <ul>
 	 * <li>undo</li>
 	 * <li>redo</li>
@@ -54,14 +52,12 @@ public class TextInputContextMenu extends ContextMenu {
 	 * <li>Select all</li>
 	 * </ul>
 	 *
-	 * @param control         the text input component to display this
-	 *                        {@code ContextMenu}
-	 * @param menuItemClicked the second action to perform when a menu item of this
-	 *                        context menu has been clicked
+	 * @param control         the text input component to display this {@code ContextMenu}
+	 * @param menuItemClicked the second action to perform when a menu item of this context menu has
+	 *                        been clicked
 	 * @since Envoy Client v0.2-beta
-	 * @apiNote please refrain from using
-	 *          {@link ContextMenu#setOnShowing(EventHandler)} as this is already
-	 *          used by this component
+	 * @apiNote please refrain from using {@link ContextMenu#setOnShowing(EventHandler)} as this is
+	 *          already used by this component
 	 */
 	public TextInputContextMenu(TextInputControl control, Consumer<ActionEvent> menuItemClicked) {
 
@@ -82,6 +78,7 @@ public class TextInputContextMenu extends ContextMenu {
 		copyMI.disableProperty().bind(control.selectedTextProperty().isEmpty());
 		deleteMI.disableProperty().bind(control.selectedTextProperty().isEmpty());
 		clearMI.disableProperty().bind(control.textProperty().isEmpty());
+		selectAllMI.disableProperty().bind(control.textProperty().isEmpty());
 		setOnShowing(e -> pasteMI.setDisable(!Clipboard.getSystemClipboard().hasString()));
 
 		selectAllMI.getProperties().put("refreshMenu", Boolean.TRUE);
@@ -89,17 +86,22 @@ public class TextInputContextMenu extends ContextMenu {
 		// Add all items to the ContextMenu
 		getItems().add(undoMI);
 		getItems().add(redoMI);
+		getItems().add(new SeparatorMenuItem());
 		getItems().add(cutMI);
 		getItems().add(copyMI);
 		getItems().add(pasteMI);
-		getItems().add(separatorMI);
+		getItems().add(new SeparatorMenuItem());
 		getItems().add(deleteMI);
 		getItems().add(clearMI);
-		getItems().add(separatorMI);
+		getItems().add(new SeparatorMenuItem());
 		getItems().add(selectAllMI);
 	}
 
-	private EventHandler<ActionEvent> addAction(Consumer<ActionEvent> originalAction, Consumer<ActionEvent> additionalAction) {
-		return e -> { originalAction.accept(e); additionalAction.accept(e); };
+	private EventHandler<ActionEvent> addAction(Consumer<ActionEvent> originalAction,
+		Consumer<ActionEvent> additionalAction) {
+		return e -> {
+			originalAction.accept(e);
+			additionalAction.accept(e);
+		};
 	}
 }

client/src/main/java/envoy/client/ui/chatscene/package-info.java

@@ -0,0 +1,7 @@
+/**
+ * Contains classes that influence the appearance and behavior of ChatScene.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+package envoy.client.ui.chatscene;

client/src/main/java/envoy/client/ui/control/AudioControl.java

@@ -6,10 +6,11 @@ import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 import javafx.scene.layout.HBox;
 
-import envoy.client.data.audio.AudioPlayer;
 import envoy.exception.EnvoyException;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.audio.AudioPlayer;
+
 /**
  * Enables the play back of audio clips through a button.
  *
@@ -18,7 +19,7 @@ import envoy.util.EnvoyLog;
  */
 public final class AudioControl extends HBox {
 
-	private AudioPlayer player = new AudioPlayer();
+	private final AudioPlayer player = new AudioPlayer();
 
 	private static final Logger logger = EnvoyLog.getLogger(AudioControl.class);
 

client/src/main/java/envoy/client/ui/control/ChatControl.java

@@ -2,16 +2,15 @@ package envoy.client.ui.control;
 
 import javafx.geometry.*;
 import javafx.scene.control.Label;
-import javafx.scene.image.*;
+import javafx.scene.image.Image;
 import javafx.scene.layout.*;
-import javafx.scene.shape.Rectangle;
 
 import envoy.client.data.*;
 import envoy.client.util.IconUtil;
 
 /**
- * Displays a chat using a contact control for the recipient and a label for the
- * unread message count.
+ * Displays a chat using a contact control for the recipient and a label for the unread message
+ * count.
  *
  * @see ContactControl
  * @author Leon Hofmeister
@@ -19,10 +18,12 @@ import envoy.client.util.IconUtil;
  */
 public final class ChatControl extends HBox {
 
-	private static final Image userIcon = IconUtil.loadIconThemeSensitive("user_icon", 32),
+	private static Image userIcon = IconUtil.loadIconThemeSensitive("user_icon", 32),
 		groupIcon = IconUtil.loadIconThemeSensitive("group_icon", 32);
 
 	/**
+	 * Creates a new {@code ChatControl}.
+	 *
 	 * @param chat the chat to display
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -31,17 +32,12 @@ public final class ChatControl extends HBox {
 		setPadding(new Insets(0, 0, 3, 0));
 
 		// Profile picture
-		ImageView	contactProfilePic	= new ImageView(chat instanceof GroupChat ? groupIcon : userIcon);
-		final var clip = new Rectangle();
-		clip.setWidth(32);
-		clip.setHeight(32);
-		clip.setArcHeight(32);
-		clip.setArcWidth(32);
-		contactProfilePic.setClip(clip);
+		var contactProfilePic =
+			new ProfilePicImageView(chat instanceof GroupChat ? groupIcon : userIcon, 32);
 		getChildren().add(contactProfilePic);
 
 		// Spacing
-		final var leftSpacing = new Region();
+		var leftSpacing = new Region();
 		leftSpacing.setPrefSize(8, 0);
 		leftSpacing.setMinSize(8, 0);
 		leftSpacing.setMaxSize(8, 0);
@@ -52,18 +48,26 @@ public final class ChatControl extends HBox {
 
 		// Unread messages
 		if (chat.getUnreadAmount() != 0) {
-			final var spacing = new Region();
+			var spacing = new Region();
 			setHgrow(spacing, Priority.ALWAYS);
 			getChildren().add(spacing);
-			final var unreadMessagesLabel = new Label(Integer.toString(chat.getUnreadAmount()));
+			var unreadMessagesLabel = new Label(
+				chat.getUnreadAmount() > 99 ? "99+" : String.valueOf(chat.getUnreadAmount()));
 			unreadMessagesLabel.setMinSize(15, 15);
-			final var vbox = new VBox();
-			vbox.setAlignment(Pos.CENTER_RIGHT);
-			unreadMessagesLabel.setAlignment(Pos.CENTER);
+			unreadMessagesLabel.setAlignment(Pos.CENTER_RIGHT);
 			unreadMessagesLabel.getStyleClass().add("unread-messages-amount");
-			vbox.getChildren().add(unreadMessagesLabel);
-			getChildren().add(vbox);
+			getChildren().add(unreadMessagesLabel);
 		}
 		getStyleClass().add("list-element");
 	}
+
+	/**
+	 * Reloads the default icons.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void reloadDefaultChatIcons() {
+		userIcon	= IconUtil.loadIconThemeSensitive("user_icon", 32);
+		groupIcon	= IconUtil.loadIconThemeSensitive("group_icon", 32);
+	}
 }

client/src/main/java/envoy/client/ui/control/ContactControl.java

@@ -6,34 +6,46 @@ import javafx.scene.layout.VBox;
 import envoy.data.*;
 
 /**
- * Displays information about a contact in two rows. The first row contains the
- * name. The second row contains the online status (user) or the member count
- * (group).
+ * Displays information about a contact in two rows. The first row contains the name. The second row
+ * contains the online status (user) or the member count (group).
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.2-beta
  */
 public final class ContactControl extends VBox {
 
+	private final Contact contact;
+
 	/**
 	 * @param contact the contact to display
 	 * @since Envoy Client v0.2-beta
 	 */
 	public ContactControl(Contact contact) {
+		this.contact = contact;
 
 		// Name label
 		final var nameLabel = new Label(contact.getName());
 		getChildren().add(nameLabel);
 
 		// Online status (user) or member count (group)
-		if (contact instanceof User) {
-			final var	status		= ((User) contact).getStatus().toString();
-			final var	statusLabel	= new Label(status);
-			statusLabel.getStyleClass().add(status.toLowerCase());
-			getChildren().add(statusLabel);
-		} else {
-			getChildren().add(new Label(contact.getContacts().size() + " members"));
-		}
+		getChildren().add(contact instanceof User ? new UserStatusLabel((User) contact)
+			: new GroupSizeLabel((Group) contact));
+
 		getStyleClass().add("list-element");
 	}
+
+	/**
+	 * Replaces the info label of this {@code ContactControl} with an updated version.
+	 * <p>
+	 * This method should be called when the status of the underlying user or the size of the
+	 * underlying group has changed.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 * @apiNote will produce buggy results if contact control gets updated so that the info label is
+	 *          no longer on index 1.
+	 */
+	public void replaceInfoLabel() {
+		getChildren().set(1, contact instanceof User ? new UserStatusLabel((User) contact)
+			: new GroupSizeLabel((Group) contact));
+	}
 }

client/src/main/java/envoy/client/ui/control/GroupSizeLabel.java

@@ -0,0 +1,23 @@
+package envoy.client.ui.control;
+
+import javafx.scene.control.Label;
+
+import envoy.data.Group;
+
+/**
+ * Displays the amount of members in a {@link Group}.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public final class GroupSizeLabel extends Label {
+
+	/**
+	 * @param recipient the group whose members to show
+	 * @since Envoy Client v0.3-beta
+	 */
+	public GroupSizeLabel(Group recipient) {
+		super(recipient.getContacts().size() + " member"
+			+ (recipient.getContacts().size() != 1 ? "s" : ""));
+	}
+}

client/src/main/java/envoy/client/ui/control/MessageControl.java

@@ -1,8 +1,6 @@
 package envoy.client.ui.control;
 
-import java.awt.Toolkit;
-import java.awt.datatransfer.StringSelection;
-import java.io.*;
+import java.io.ByteArrayInputStream;
 import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
 import java.util.Map;
@@ -12,15 +10,15 @@ import javafx.geometry.*;
 import javafx.scene.control.*;
 import javafx.scene.image.*;
 import javafx.scene.layout.*;
-import javafx.stage.FileChooser;
 
-import envoy.client.data.*;
-import envoy.client.ui.*;
-import envoy.client.util.IconUtil;
 import envoy.data.*;
 import envoy.data.Message.MessageStatus;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.*;
+import envoy.client.net.Client;
+import envoy.client.util.*;
+
 /**
  * This class transforms a single {@link Message} into a UI component.
  *
@@ -32,21 +30,25 @@ public final class MessageControl extends Label {
 
 	private final boolean ownMessage;
 
-	private final LocalDB		localDB			= Context.getInstance().getLocalDB();
-	private final SceneContext	sceneContext	= Context.getInstance().getSceneContext();
+	private final LocalDB	localDB	= context.getLocalDB();
+	private final Client	client	= context.getClient();
 
-	private static final DateTimeFormatter			dateFormat		= DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm:ss")
+	private static final Context					context			= Context.getInstance();
+	private static final DateTimeFormatter			dateFormat		=
+		DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm:ss")
 			.withZone(ZoneId.systemDefault());
-	private static final Map<MessageStatus, Image>	statusImages	= IconUtil.loadByEnum(MessageStatus.class, 16);
-	private static final Settings					settings		= Settings.getInstance();
-	private static final Logger						logger			= EnvoyLog.getLogger(MessageControl.class);
+	private static final Map<MessageStatus, Image>	statusImages	=
+		IconUtil.loadByEnum(MessageStatus.class, 16);
+	private static final Logger						logger			=
+		EnvoyLog.getLogger(MessageControl.class);
 
 	/**
-	 *
 	 * @param message the message that should be formatted
 	 * @since Envoy Client v0.1-beta
 	 */
 	public MessageControl(Message message) {
+		ownMessage = message.getSenderID() == localDB.getUser().getID();
+
 		// Creating the underlying VBox and the dateLabel
 		final var hbox = new HBox();
 		if (message.getSenderID() != localDB.getUser().getID() && message instanceof GroupMessage) {
@@ -68,17 +70,39 @@ public final class MessageControl extends Label {
 
 		// Creating the actions for the MenuItems
 		final var	contextMenu	= new ContextMenu();
-		final var	copyMenuItem	= new MenuItem("Copy");
-		final var	deleteMenuItem	= new MenuItem("Delete");
+		final var	items		= contextMenu.getItems();
+
+		// Copy message action
+		if (!message.getText().isEmpty()) {
+			final var copyMenuItem = new MenuItem("Copy Text");
+			copyMenuItem.setOnAction(e -> MessageUtil.copyMessageText(message));
+			items.add(copyMenuItem);
+		}
+
+		// Delete message
+		final var deleteMenuItem = new MenuItem("Delete locally");
+		deleteMenuItem.setOnAction(e -> MessageUtil.deleteMessage(message));
+		items.add(deleteMenuItem);
+
+		// As long as these types of messages are not implemented and no caches are
+		// defined for them, we only want them to appear when being online
+		if (client.isOnline()) {
+
+			// Forward menu item
 			final var forwardMenuItem = new MenuItem("Forward");
+			forwardMenuItem.setOnAction(e -> MessageUtil.forwardMessage(message));
+			items.add(forwardMenuItem);
+
+			// Quote menu item
 			final var quoteMenuItem = new MenuItem("Quote");
+			quoteMenuItem.setOnAction(e -> MessageUtil.quoteMessage(message));
+			items.add(quoteMenuItem);
+		}
+
+		// Info actions
 		final var infoMenuItem = new MenuItem("Info");
-		copyMenuItem.setOnAction(e -> copyMessage(message));
-		deleteMenuItem.setOnAction(e -> deleteMessage(message));
-		forwardMenuItem.setOnAction(e -> forwardMessage(message));
-		quoteMenuItem.setOnAction(e -> quoteMessage(message));
 		infoMenuItem.setOnAction(e -> loadMessageInfoScene(message));
-		contextMenu.getItems().addAll(copyMenuItem, deleteMenuItem, forwardMenuItem, quoteMenuItem, infoMenuItem);
+		items.add(infoMenuItem);
 
 		// Handling message attachment display
 		// TODO: Add missing attachment types
@@ -86,7 +110,9 @@ public final class MessageControl extends Label {
 			switch (message.getAttachment().getType()) {
 				case PICTURE:
 					vbox.getChildren()
-						.add(new ImageView(new Image(new ByteArrayInputStream(message.getAttachment().getData()), 256, 256, true, true)));
+						.add(new ImageView(
+							new Image(new ByteArrayInputStream(message.getAttachment().getData()),
+								256, 256, true, true)));
 					break;
 				case VIDEO:
 					break;
@@ -97,8 +123,8 @@ public final class MessageControl extends Label {
 					break;
 			}
 			final var saveAttachment = new MenuItem("Save attachment");
-			saveAttachment.setOnAction(e -> saveAttachment(message));
-			contextMenu.getItems().add(saveAttachment);
+			saveAttachment.setOnAction(e -> MessageUtil.saveAttachment(message));
+			items.add(saveAttachment);
 		}
 		// Creating the textLabel
 		final var textLabel = new Label(message.getText());
@@ -116,12 +142,9 @@ public final class MessageControl extends Label {
 			hBoxBottom.getChildren().add(statusIcon);
 			hBoxBottom.setAlignment(Pos.BOTTOM_RIGHT);
 			getStyleClass().add("own-message");
-			ownMessage = true;
 			hbox.setAlignment(Pos.CENTER_RIGHT);
-		} else {
+		} else
 			getStyleClass().add("received-message");
-			ownMessage = false;
-		}
 		vbox.getChildren().add(hBoxBottom);
 		// Adjusting height and weight of the cell to the corresponding ListView
 		paddingProperty().setValue(new Insets(5, 20, 5, 20));
@@ -129,44 +152,13 @@ public final class MessageControl extends Label {
 		setGraphic(vbox);
 	}
 
-	// Context Menu actions
-
-	private void copyMessage(Message message) {
-		Toolkit.getDefaultToolkit().getSystemClipboard().setContents(new StringSelection(message.getText()), null);
-	}
-
-	private void deleteMessage(Message message) { logger.log(Level.FINEST, "message deletion was requested for " + message); }
-
-	private void forwardMessage(Message message) { logger.log(Level.FINEST, "message forwarding was requested for " + message); }
-
-	private void quoteMessage(Message message) { logger.log(Level.FINEST, "message quotation was requested for " + message); }
-
-	private void loadMessageInfoScene(Message message) { logger.log(Level.FINEST, "message info scene was requested for " + message); }
-
-	private void saveAttachment(Message message) {
-		File		file;
-		final var	fileName			= message.getAttachment().getName();
-		final var	downloadLocation	= settings.getDownloadLocation();
-		// Show save file dialog, if the user did not opt-out
-		if (!settings.isDownloadSavedWithoutAsking()) {
-			final var fileChooser = new FileChooser();
-			fileChooser.setInitialFileName(fileName);
-			fileChooser.setInitialDirectory(downloadLocation);
-			file = fileChooser.showSaveDialog(sceneContext.getStage());
-		} else file = new File(downloadLocation, fileName);
-
-		// A file was selected
-		if (file != null) try (FileOutputStream fos = new FileOutputStream(file)) {
-			fos.write(message.getAttachment().getData());
-			logger.log(Level.FINE, "Attachment of message was saved at " + file.getAbsolutePath());
-		} catch (final IOException e) {
-			logger.log(Level.WARNING, "Could not save attachment of " + message + ": ", e);
-		}
+	private void loadMessageInfoScene(Message message) {
+		logger.log(Level.FINEST, "message info scene was requested for " + message);
 	}
 
 	/**
-	 * @return whether the message stored by this {@code MessageControl} has been
-	 *         sent by this user of Envoy
+	 * @return whether the message stored by this {@code MessageControl} has been sent by this user
+	 *         of Envoy
 	 * @since Envoy Client v0.1-beta
 	 */
 	public boolean isOwnMessage() { return ownMessage; }

client/src/main/java/envoy/client/ui/control/ProfilePicImageView.java

@@ -16,7 +16,9 @@ public final class ProfilePicImageView extends ImageView {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public ProfilePicImageView() { this(null); }
+	public ProfilePicImageView() {
+		this(null);
+	}
 
 	/**
 	 * Creates a new {@code ProfilePicImageView}.
@@ -24,17 +26,20 @@ public final class ProfilePicImageView extends ImageView {
 	 * @param image the image to display
 	 * @since Envoy Client v0.2-beta
 	 */
-	public ProfilePicImageView(Image image) { this(image, 40); }
+	public ProfilePicImageView(Image image) {
+		this(image, 40);
+	}
 
 	/**
 	 * Creates a new {@code ProfilePicImageView}.
 	 *
 	 * @param image           the image to display
-	 * @param sizeAndRounding the size and rounding for a circular
-	 *                        {@code ProfilePicImageView}
+	 * @param sizeAndRounding the size and rounding for a circular {@code ProfilePicImageView}
 	 * @since Envoy Client v0.2-beta
 	 */
-	public ProfilePicImageView(Image image, double sizeAndRounding) { this(image, sizeAndRounding, sizeAndRounding); }
+	public ProfilePicImageView(Image image, double sizeAndRounding) {
+		this(image, sizeAndRounding, sizeAndRounding);
+	}
 
 	/**
 	 * Creates a new {@code ProfilePicImageView}.

client/src/main/java/envoy/client/ui/control/QuickSelectControl.java

@@ -0,0 +1,94 @@
+package envoy.client.ui.control;
+
+import java.util.function.Consumer;
+
+import javafx.geometry.*;
+import javafx.scene.control.*;
+import javafx.scene.image.ImageView;
+import javafx.scene.layout.*;
+import javafx.scene.shape.Rectangle;
+
+import envoy.data.User;
+
+import envoy.client.util.IconUtil;
+
+/**
+ * Displays an {@link User} as a quick select control which is used in the quick select list.
+ *
+ * @author Maximilian Käfer
+ * @since Envoy Client v0.3-beta
+ */
+public class QuickSelectControl extends VBox {
+
+	private final User user;
+
+	/**
+	 * Creates an instance of the {@code QuickSelectControl}.
+	 *
+	 * @param user   the contact whose data is used to create this instance.
+	 * @param action the action to perform when a contact is removed with this control as a
+	 *               parameter
+	 * @since Envoy Client v0.3-beta
+	 */
+	public QuickSelectControl(User user, Consumer<QuickSelectControl> action) {
+		this.user = user;
+		setPadding(new Insets(1, 0, 0, 0));
+		setPrefWidth(37);
+		setMaxWidth(37);
+		setMinWidth(37);
+		var stackPane = new StackPane();
+		stackPane.setAlignment(Pos.TOP_CENTER);
+
+		// Profile picture
+		var picHold = new VBox();
+		picHold.setPadding(new Insets(2, 0, 0, 0));
+		picHold.setPrefHeight(35);
+		picHold.setMaxHeight(35);
+		picHold.setMinHeight(35);
+		var			contactProfilePic	=
+			new ImageView(IconUtil.loadIconThemeSensitive("user_icon", 32));
+		final var	clip				= new Rectangle();
+		clip.setWidth(32);
+		clip.setHeight(32);
+		clip.setArcHeight(32);
+		clip.setArcWidth(32);
+		contactProfilePic.setClip(clip);
+		picHold.getChildren().add(contactProfilePic);
+		stackPane.getChildren().add(picHold);
+
+		var hBox = new HBox();
+		hBox.setPrefHeight(12);
+		hBox.setMaxHeight(12);
+		hBox.setMinHeight(12);
+		var region = new Region();
+		hBox.getChildren().add(region);
+		HBox.setHgrow(region, Priority.ALWAYS);
+
+		var removeBtn = new Button();
+		removeBtn.setPrefSize(12, 12);
+		removeBtn.setMaxSize(12, 12);
+		removeBtn.setMinSize(12, 12);
+		removeBtn.setOnMouseClicked(evt -> action.accept(this));
+		removeBtn.setId("remove-button");
+		hBox.getChildren().add(removeBtn);
+		stackPane.getChildren().add(hBox);
+		getChildren().add(stackPane);
+
+		var nameLabel = new Label();
+		nameLabel.setPrefSize(35, 20);
+		nameLabel.setMaxSize(35, 20);
+		nameLabel.setMinSize(35, 20);
+		nameLabel.setText(user.getName());
+		nameLabel.setAlignment(Pos.TOP_CENTER);
+		nameLabel.setPadding(new Insets(0, 5, 0, 0));
+		getChildren().add(nameLabel);
+
+		getStyleClass().add("quick-select");
+	}
+
+	/**
+	 * @return the user whose data is used in this instance
+	 * @since Envoy Client v0.3-beta
+	 */
+	public User getUser() { return user; }
+}

client/src/main/java/envoy/client/ui/control/UserStatusLabel.java

@@ -0,0 +1,23 @@
+package envoy.client.ui.control;
+
+import javafx.scene.control.Label;
+
+import envoy.data.User;
+
+/**
+ * Displays the status of a {@link User}.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public final class UserStatusLabel extends Label {
+
+	/**
+	 * @param user the user whose status to display
+	 * @since Envoy Client v0.3-beta
+	 */
+	public UserStatusLabel(User user) {
+		super(user.getStatus().toString());
+		getStyleClass().add(user.getStatus().toString().toLowerCase());
+	}
+}

client/src/main/java/envoy/client/ui/controller/ChatScene.java

@@ -1,12 +1,14 @@
 package envoy.client.ui.controller;
 
+import static envoy.client.ui.SceneInfo.SETTINGS_SCENE;
+
 import java.awt.Toolkit;
 import java.awt.datatransfer.StringSelection;
 import java.io.*;
 import java.nio.file.Files;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
-import java.util.Random;
+import java.util.Map;
 import java.util.logging.*;
 
 import javafx.animation.RotateTransition;
@@ -14,37 +16,38 @@ import javafx.application.Platform;
 import javafx.collections.ObservableList;
 import javafx.collections.transformation.FilteredList;
 import javafx.fxml.*;
+import javafx.geometry.Pos;
 import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 import javafx.scene.image.*;
 import javafx.scene.input.*;
-import javafx.scene.layout.*;
+import javafx.scene.layout.HBox;
 import javafx.scene.paint.Color;
 import javafx.scene.shape.Rectangle;
 import javafx.stage.FileChooser;
 import javafx.util.Duration;
 
-import envoy.client.data.*;
-import envoy.client.data.audio.AudioRecorder;
-import envoy.client.data.commands.*;
-import envoy.client.event.*;
-import envoy.client.helper.ShutdownHelper;
-import envoy.client.net.*;
-import envoy.client.ui.*;
-import envoy.client.ui.SceneContext.SceneInfo;
-import envoy.client.ui.control.*;
-import envoy.client.ui.listcell.*;
-import envoy.client.util.*;
+import dev.kske.eventbus.core.*;
+import dev.kske.eventbus.core.Event;
+
 import envoy.data.*;
 import envoy.data.Attachment.AttachmentType;
 import envoy.data.Message.MessageStatus;
 import envoy.event.*;
-import envoy.event.contact.ContactOperation;
+import envoy.event.contact.UserOperation;
 import envoy.exception.EnvoyException;
 import envoy.util.EnvoyLog;
 
-import dev.kske.eventbus.*;
-import dev.kske.eventbus.Event;
+import envoy.client.data.*;
+import envoy.client.data.audio.AudioRecorder;
+import envoy.client.data.shortcuts.KeyboardMapping;
+import envoy.client.event.*;
+import envoy.client.net.*;
+import envoy.client.ui.*;
+import envoy.client.ui.chatscene.*;
+import envoy.client.ui.control.*;
+import envoy.client.ui.listcell.*;
+import envoy.client.util.*;
 
 /**
  * Controller for the chat scene.
@@ -52,13 +55,7 @@ import dev.kske.eventbus.Event;
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
  */
-public final class ChatScene implements EventListener, Restorable {
-
-	@FXML
-	private GridPane scene;
-
-	@FXML
-	private Label contactLabel;
+public final class ChatScene implements Restorable, KeyboardMapping {
 
 	@FXML
 	private ListView<Message> messageList;
@@ -87,27 +84,21 @@ public final class ChatScene implements EventListener, Restorable {
 	@FXML
 	private Button newContactButton;
 
-	@FXML
-	private TextArea messageTextArea;
-
 	@FXML
 	private Label remainingChars;
 
 	@FXML
 	private Label infoLabel;
 
-	@FXML
-	private MenuItem deleteContactMenuItem;
-
-	@FXML
-	private ImageView attachmentView;
-
 	@FXML
 	private Label topBarContactLabel;
 
 	@FXML
 	private Label topBarStatusLabel;
 
+	@FXML
+	private ImageView attachmentView;
+
 	@FXML
 	private ImageView clientProfilePic;
 
@@ -115,10 +106,10 @@ public final class ChatScene implements EventListener, Restorable {
 	private ImageView recipientProfilePic;
 
 	@FXML
-	private TextArea contactSearch;
+	private TextArea messageTextArea;
 
 	@FXML
-	private VBox contactOperations;
+	private TextArea contactSearch;
 
 	@FXML
 	private TabPane tabPane;
@@ -132,22 +123,26 @@ public final class ChatScene implements EventListener, Restorable {
 	@FXML
 	private HBox contactSpecificOnlineOperations;
 
+	@FXML
+	private HBox ownContactControl;
+
 	private Chat				currentChat;
 	private FilteredList<Chat>	chats;
-	private boolean				recording;
 	private Attachment			pendingAttachment;
 	private boolean				postingPermanentlyDisabled;
 	private boolean				isCustomAttachmentImage;
+	private ChatSceneCommands	commands;
 
 	private final LocalDB		localDB				= context.getLocalDB();
 	private final Client		client				= context.getClient();
 	private final WriteProxy	writeProxy			= context.getWriteProxy();
 	private final SceneContext	sceneContext		= context.getSceneContext();
 	private final AudioRecorder	recorder			= new AudioRecorder();
-	private final SystemCommandMap	messageTextAreaCommands	= new SystemCommandMap();
-	private final Tooltip			onlyIfOnlineTooltip		= new Tooltip("You need to be online to do this");
+	private final Tooltip		onlyIfOnlineTooltip	=
+		new Tooltip("You need to be online to do this");
 
-	private static Image DEFAULT_ATTACHMENT_VIEW_IMAGE = IconUtil.loadIconThemeSensitive("attachment_present", 20);
+	private static Image DEFAULT_ATTACHMENT_VIEW_IMAGE =
+		IconUtil.loadIconThemeSensitive("attachment_present", 20);
 
 	private static final Settings	settings			= Settings.getInstance();
 	private static final EventBus	eventBus			= EventBus.getInstance();
@@ -164,22 +159,28 @@ public final class ChatScene implements EventListener, Restorable {
 	@FXML
 	private void initialize() {
 		eventBus.registerListener(this);
+		commands = new ChatSceneCommands(messageList, this);
 
 		// Initialize message and user rendering
 		messageList.setCellFactory(MessageListCell::new);
-		chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));
+		chatList.setCellFactory(ChatListCell::new);
 
 		// JavaFX provides an internal way of populating the context menu of a text
 		// area.
 		// We, however, need additional functionality.
-		messageTextArea.setContextMenu(new TextInputContextMenu(messageTextArea, e -> checkKeyCombination(null)));
+		messageTextArea.setContextMenu(
+			new TextInputContextMenu(messageTextArea, e -> checkKeyCombination(null)));
 
 		// Set the icons of buttons and image views
-		settingsButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
-		voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
-		attachmentButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
+		settingsButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("settings", 22)));
+		voiceButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+		attachmentButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
 		attachmentView.setImage(DEFAULT_ATTACHMENT_VIEW_IMAGE);
-		messageSearchButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
+		messageSearchButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
 		clientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
 		onlyIfOnlineTooltip.setShowDelay(Duration.millis(250));
 		final var clip = new Rectangle();
@@ -190,20 +191,25 @@ public final class ChatScene implements EventListener, Restorable {
 		clientProfilePic.setClip(clip);
 
 		chatList.setItems(chats = new FilteredList<>(localDB.getChats()));
-		contactLabel.setText(localDB.getUser().getName());
 
-		initializeSystemCommandsMap();
+		// Set the design of the box in the upper-left corner
+		generateOwnStatusControl();
 
 		Platform.runLater(() -> {
 			final var online = client.isOnline();
+
 			// no check will be performed in case it has already been disabled - a negative
 			// GroupCreationResult might have been returned
-			if (!newGroupButton.isDisabled()) newGroupButton.setDisable(!online);
+			if (!newGroupButton.isDisabled())
+				newGroupButton.setDisable(!online);
 			newContactButton.setDisable(!online);
-			if (online) try {
+			if (online)
+				try {
 					Tooltip.uninstall(contactSpecificOnlineOperations, onlyIfOnlineTooltip);
-				contactSearchTab.setContent(new FXMLLoader().load(getClass().getResourceAsStream("/fxml/ContactSearchTab.fxml")));
-				groupCreationTab.setContent(new FXMLLoader().load(getClass().getResourceAsStream("/fxml/GroupCreationTab.fxml")));
+					contactSearchTab.setContent(new FXMLLoader()
+						.load(getClass().getResourceAsStream("/fxml/ContactSearchTab.fxml")));
+					groupCreationTab.setContent(new FXMLLoader()
+						.load(getClass().getResourceAsStream("/fxml/GroupCreationTab.fxml")));
 				} catch (final IOException e) {
 					logger.log(Level.SEVERE, "An error occurred when attempting to load tabs: ", e);
 				}
@@ -214,33 +220,40 @@ public final class ChatScene implements EventListener, Restorable {
 		});
 	}
 
-	@Event(eventType = BackEvent.class)
-	private void onBackEvent() { tabPane.getSelectionModel().select(Tabs.CONTACT_LIST.ordinal()); }
+	@Event(BackEvent.class)
+	private void onBackEvent() {
+		tabPane.getSelectionModel().select(Tabs.CONTACT_LIST.ordinal());
+	}
 
-	@Event(includeSubtypes = true)
+	@Event
+	@Polymorphic
 	private void onMessage(Message message) {
 
 		// The sender of the message is the recipient of the chat
 		// Exceptions: this user is the sender (sync) or group message (group is
 		// recipient)
-		final boolean	ownMessage	= message.getSenderID() == localDB.getUser().getID();
-		final var		recipientID	= message instanceof GroupMessage || ownMessage ? message.getRecipientID() : message.getSenderID();
+		final var	ownMessage	= message.getSenderID() == localDB.getUser().getID();
+		final var	recipientID	=
+			message instanceof GroupMessage || ownMessage ? message.getRecipientID()
+				: message.getSenderID();
 
 		localDB.getChat(recipientID).ifPresent(chat -> {
+			Platform.runLater(() -> {
 				chat.insert(message);
 
 				// Read current chat or increment unread amount
 				if (chat.equals(currentChat)) {
 					currentChat.read(writeProxy);
-				Platform.runLater(this::scrollToMessageListEnd);
-			} else if (!ownMessage && message.getStatus() != MessageStatus.READ) chat.incrementUnreadAmount();
+					scrollToMessageListEnd();
+				} else if (!ownMessage && message.getStatus() != MessageStatus.READ)
+					chat.incrementUnreadAmount();
 
 				// Move chat with most recent unread messages to the top
-			Platform.runLater(() -> {
 				chats.getSource().remove(chat);
 				((ObservableList<Chat>) chats.getSource()).add(0, chat);
 
-				if (chat.equals(currentChat)) chatList.getSelectionModel().select(0);
+				if (chat.equals(currentChat))
+					chatList.getSelectionModel().select(0);
 			});
 		});
 	}
@@ -250,30 +263,49 @@ public final class ChatScene implements EventListener, Restorable {
 
 		// Update UI if in current chat and the current user was the sender of the
 		// message
-		if (currentChat != null) localDB.getMessage(evt.getID())
+		if (currentChat != null)
+			localDB.getMessage(evt.getID())
 				.filter(msg -> msg.getSenderID() == client.getSender().getID())
 				.ifPresent(msg -> Platform.runLater(messageList::refresh));
 	}
 
-	@Event(eventType = UserStatusChange.class)
-	private void onUserStatusChange() { Platform.runLater(chatList::refresh); }
+	@Event
+	private void onUserStatusChange(UserStatusChange statusChange) {
+		Platform.runLater(() -> {
+			chatList.refresh();
+
+			// Replacing the display in the top bar
+			if (currentChat != null && currentChat.getRecipient().getID() == statusChange.getID()) {
+				topBarStatusLabel.getStyleClass().clear();
+				topBarStatusLabel.setText(statusChange.get().toString());
+				topBarStatusLabel.getStyleClass().add(statusChange.get().toString().toLowerCase());
+			}
+		});
+	}
 
 	@Event
-	private void onContactOperation(ContactOperation operation) {
-		final var contact = operation.get();
-		switch (operation.getOperationType()) {
-			case ADD:
-				if (contact instanceof User) localDB.getUsers().put(contact.getName(), (User) contact);
-				final var chat = contact instanceof User ? new Chat(contact) : new GroupChat(client.getSender(), contact);
-				Platform.runLater(() -> ((ObservableList<Chat>) chats.getSource()).add(0, chat));
-				break;
-			case REMOVE:
-				Platform.runLater(() -> chats.getSource().removeIf(c -> c.getRecipient().equals(contact)));
-				break;
-		}
+	private void onUserOperation(UserOperation operation) {
+
+		// All ADD dependent logic resides in LocalDB
+		if (operation.getOperationType().equals(ElementOperation.REMOVE))
+			Platform.runLater(() -> disableChat(new ContactDisabled(operation.get())));
 	}
 
-	@Event(eventType = NoAttachments.class)
+	@Event
+	private void onGroupResize(GroupResize resize) {
+		final var chatFound = localDB.getChat(resize.getGroupID());
+		chatFound.ifPresent(chat -> Platform.runLater(() -> {
+			chatList.refresh();
+
+			// Update the top-bar status label if all conditions apply
+			if (currentChat != null && currentChat.getRecipient().equals(chat.getRecipient()))
+				topBarStatusLabel
+					.setText(chat.getRecipient().getContacts().size() + " member"
+						+ (currentChat.getRecipient().getContacts().size() != 1 ? "s" : ""));
+		}));
+	}
+
+	@Event(NoAttachments.class)
 	private void onNoAttachments() {
 		Platform.runLater(() -> {
 			attachmentButton.setDisable(true);
@@ -287,59 +319,50 @@ public final class ChatScene implements EventListener, Restorable {
 	}
 
 	@Event
-	private void onGroupCreationResult(GroupCreationResult result) { Platform.runLater(() -> newGroupButton.setDisable(!result.get())); }
+	@Priority(150)
+	private void onGroupCreationResult(GroupCreationResult result) {
+		Platform.runLater(() -> newGroupButton.setDisable(result.get() == null));
+	}
 
-	@Event(eventType = ThemeChangeEvent.class)
+	@Event(ThemeChangeEvent.class)
 	private void onThemeChange() {
-		settingsButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
-		voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
-		attachmentButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
+		ChatControl.reloadDefaultChatIcons();
+		settingsButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
+		voiceButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+		attachmentButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
 		DEFAULT_ATTACHMENT_VIEW_IMAGE = IconUtil.loadIconThemeSensitive("attachment_present", 20);
-		attachmentView.setImage(isCustomAttachmentImage ? attachmentView.getImage() : DEFAULT_ATTACHMENT_VIEW_IMAGE);
-		messageSearchButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
+		attachmentView.setImage(
+			isCustomAttachmentImage ? attachmentView.getImage() : DEFAULT_ATTACHMENT_VIEW_IMAGE);
+		messageSearchButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
 		clientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
 		chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));
 		messageList.setCellFactory(MessageListCell::new);
-		// TODO: cache image
-		if (currentChat.getRecipient() instanceof User) recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
-		else recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
+		if (currentChat != null)
+			if (currentChat.getRecipient() instanceof User)
+				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
+			else
+				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
 	}
 
-	@Event(eventType = Logout.class, priority = 200)
-	private void onLogout() { eventBus.removeListener(this); }
+	@Event(Logout.class)
+	@Priority(200)
+	private void onLogout() {
+		eventBus.removeListener(this);
+	}
 
-	/**
-	 * Initializes all {@code SystemCommands} used in {@code ChatScene}.
-	 *
-	 * @since Envoy Client v0.2-beta
-	 */
-	private void initializeSystemCommandsMap() {
-		final var builder = new SystemCommandBuilder(messageTextAreaCommands);
-
-		// Do A Barrel roll initialization
-		final var random = new Random();
-		builder.setAction(text -> doABarrelRoll(Integer.parseInt(text.get(0)), Double.parseDouble(text.get(1))))
-			.setDefaults(Integer.toString(random.nextInt(3) + 1), Double.toString(random.nextDouble() * 3 + 1))
-			.setDescription("See for yourself :)")
-			.setNumberOfArguments(2)
-			.build("dabr");
-
-		// Logout initialization
-		builder.setAction(text -> ShutdownHelper.logout()).setNumberOfArguments(0).setDescription("Logs you out.").build("logout");
-
-		// Exit initialization
-		builder.setAction(text -> ShutdownHelper.exit()).setNumberOfArguments(0).setDescription("Exits the program").build("exit", false);
-		builder.build("q");
-
-		// Open settings scene initialization
-		builder.setAction(text -> sceneContext.load(SceneInfo.SETTINGS_SCENE))
-			.setNumberOfArguments(0)
-			.setDescription("Opens the settings screen")
-			.build("settings");
+	@Event(AccountDeletion.class)
+	private void onAccountDeletion() {
+		Platform.runLater(chatList::refresh);
 	}
 
 	@Override
-	public void onRestore() { updateRemainingCharsLabel(); }
+	public void onRestore() {
+		updateRemainingCharsLabel();
+	}
 
 	/**
 	 * Actions to perform when the list of contacts has been clicked.
@@ -348,9 +371,13 @@ public final class ChatScene implements EventListener, Restorable {
 	 */
 	@FXML
 	private void chatListClicked() {
-		if (chatList.getSelectionModel().isEmpty()) return;
+		if (chatList.getSelectionModel().isEmpty())
+			return;
+		final var chat = chatList.getSelectionModel().getSelectedItem();
+		if (chat == null)
+			return;
 
-		final var user = chatList.getSelectionModel().getSelectedItem().getRecipient();
+		final var user = chat.getRecipient();
 		if (user != null && (currentChat == null || !user.equals(currentChat.getRecipient()))) {
 
 			// LEON: JFC <===> JAVA FRIED CHICKEN <=/=> Java Foundation Classes
@@ -362,7 +389,6 @@ public final class ChatScene implements EventListener, Restorable {
 			final var scrollIndex = messageList.getItems().size() - currentChat.getUnreadAmount();
 			messageList.scrollTo(scrollIndex);
 			logger.log(Level.FINEST, "Loading chat with " + user + " at index " + scrollIndex);
-			deleteContactMenuItem.setText("Delete " + user.getName());
 
 			// Read the current chat
 			currentChat.read(writeProxy);
@@ -370,38 +396,50 @@ public final class ChatScene implements EventListener, Restorable {
 			// Discard the pending attachment
 			if (recorder.isRecording()) {
 				recorder.cancel();
-				recording = false;
+				voiceButton.setGraphic(new ImageView(
+					IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+				voiceButton.setText(null);
 			}
 			pendingAttachment = null;
 			updateAttachmentView(false);
 
 			remainingChars.setVisible(true);
 			remainingChars
-				.setText(String.format("remaining chars: %d/%d", MAX_MESSAGE_LENGTH - messageTextArea.getText().length(), MAX_MESSAGE_LENGTH));
+				.setText(String.format("remaining chars: %d/%d",
+					MAX_MESSAGE_LENGTH - messageTextArea.getText().length(), MAX_MESSAGE_LENGTH));
 		}
-		messageTextArea.setDisable(currentChat == null || postingPermanentlyDisabled);
-		voiceButton.setDisable(!recorder.isSupported());
-		attachmentButton.setDisable(false);
+
+		// Enable or disable the necessary UI controls
+		final var chatEditable = currentChat == null || currentChat.isDisabled();
+		messageTextArea.setDisable(chatEditable || postingPermanentlyDisabled);
+		voiceButton.setDisable(!recorder.isSupported() || chatEditable);
+		attachmentButton.setDisable(chatEditable);
 		chatList.refresh();
 
+		// Design the top bar
 		if (currentChat != null) {
 			topBarContactLabel.setText(currentChat.getRecipient().getName());
+			topBarContactLabel.setVisible(true);
+			topBarStatusLabel.setVisible(true);
 			if (currentChat.getRecipient() instanceof User) {
-				final String status = ((User) currentChat.getRecipient()).getStatus().toString();
+				final var status = ((User) currentChat.getRecipient()).getStatus().toString();
 				topBarStatusLabel.setText(status);
+				topBarStatusLabel.getStyleClass().clear();
 				topBarStatusLabel.getStyleClass().add(status.toLowerCase());
 				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
 			} else {
-				topBarStatusLabel.setText(currentChat.getRecipient().getContacts().size() + " members");
+				topBarStatusLabel
+					.setText(currentChat.getRecipient().getContacts().size() + " member"
+						+ (currentChat.getRecipient().getContacts().size() != 1 ? "s" : ""));
+				topBarStatusLabel.getStyleClass().clear();
 				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
 			}
-			final Rectangle clip = new Rectangle();
+			final var clip = new Rectangle();
 			clip.setWidth(43);
 			clip.setHeight(43);
 			clip.setArcHeight(43);
 			clip.setArcWidth(43);
 			recipientProfilePic.setClip(clip);
-
 			messageSearchButton.setVisible(true);
 		}
 	}
@@ -412,7 +450,9 @@ public final class ChatScene implements EventListener, Restorable {
 	 * @since Envoy Client v0.1-beta
 	 */
 	@FXML
-	private void settingsButtonClicked() { sceneContext.load(SceneContext.SceneInfo.SETTINGS_SCENE); }
+	private void settingsButtonClicked() {
+		sceneContext.load(SETTINGS_SCENE);
+	}
 
 	/**
 	 * Actions to perform when the "Add Contact" - Button has been clicked.
@@ -420,29 +460,35 @@ public final class ChatScene implements EventListener, Restorable {
 	 * @since Envoy Client v0.1-beta
 	 */
 	@FXML
-	private void addContactButtonClicked() { tabPane.getSelectionModel().select(Tabs.CONTACT_SEARCH.ordinal()); }
+	private void addContactButtonClicked() {
+		tabPane.getSelectionModel().select(Tabs.CONTACT_SEARCH.ordinal());
+	}
 
 	@FXML
-	private void groupCreationButtonClicked() { tabPane.getSelectionModel().select(Tabs.GROUP_CREATION.ordinal()); }
+	private void groupCreationButtonClicked() {
+		tabPane.getSelectionModel().select(Tabs.GROUP_CREATION.ordinal());
+	}
 
 	@FXML
 	private void voiceButtonClicked() {
 		new Thread(() -> {
 			try {
-				if (!recording) {
-					recording = true;
+				if (!recorder.isRecording()) {
 					Platform.runLater(() -> {
 						voiceButton.setText("Recording");
-						voiceButton.setGraphic(new ImageView(IconUtil.loadIcon("microphone_recording", DEFAULT_ICON_SIZE)));
+						voiceButton.setGraphic(new ImageView(
+							IconUtil.loadIcon("microphone_recording", DEFAULT_ICON_SIZE)));
 					});
 					recorder.start();
 				} else {
 					pendingAttachment = new Attachment(recorder.finish(), "Voice_recording_"
-							+ DateTimeFormatter.ofPattern("yyyy_MM_dd-HH_mm_ss").format(LocalDateTime.now()) + "." + AudioRecorder.FILE_FORMAT,
+						+ DateTimeFormatter.ofPattern("yyyy_MM_dd-HH_mm_ss")
+							.format(LocalDateTime.now())
+						+ "." + AudioRecorder.FILE_FORMAT,
 						AttachmentType.VOICE);
-					recording			= false;
 					Platform.runLater(() -> {
-						voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+						voiceButton.setGraphic(new ImageView(
+							IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
 						voiceButton.setText(null);
 						checkPostConditions(false);
 						updateAttachmentView(true);
@@ -450,7 +496,8 @@ public final class ChatScene implements EventListener, Restorable {
 				}
 			} catch (final EnvoyException e) {
 				logger.log(Level.SEVERE, "Could not record audio: ", e);
-				Platform.runLater(new Alert(AlertType.ERROR, "Could not record audio")::showAndWait);
+				Platform
+					.runLater(new Alert(AlertType.ERROR, "Could not record audio")::showAndWait);
 			}
 		}).start();
 	}
@@ -472,7 +519,8 @@ public final class ChatScene implements EventListener, Restorable {
 
 			// Check max file size
 			if (file.length() > 16E6) {
-				new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 16MB!").showAndWait();
+				new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 16MB!")
+					.showAndWait();
 				return;
 			}
 
@@ -494,7 +542,8 @@ public final class ChatScene implements EventListener, Restorable {
 				checkPostConditions(false);
 				// Setting the preview image as image of the attachmentView
 				if (type == AttachmentType.PICTURE) {
-					attachmentView.setImage(new Image(new ByteArrayInputStream(fileBytes), DEFAULT_ICON_SIZE, DEFAULT_ICON_SIZE, true, true));
+					attachmentView.setImage(new Image(new ByteArrayInputStream(fileBytes),
+						DEFAULT_ICON_SIZE, DEFAULT_ICON_SIZE, true, true));
 					isCustomAttachmentImage = true;
 				}
 				attachmentView.setVisible(true);
@@ -505,14 +554,13 @@ public final class ChatScene implements EventListener, Restorable {
 	}
 
 	/**
-	 * Rotates every element in our application by {@code rotations}*360° in
-	 * {@code an}.
+	 * Rotates every element in our application by {@code rotations}*360° in {@code an}.
 	 *
 	 * @param rotations     the amount of times the scene is rotated by 360°
 	 * @param animationTime the time in seconds that this animation lasts
 	 * @since Envoy Client v0.1-beta
 	 */
-	private void doABarrelRoll(int rotations, double animationTime) {
+	public void doABarrelRoll(int rotations, double animationTime) {
 		// Limiting the rotations and duration
 		rotations		= Math.min(rotations, 100000);
 		rotations		= Math.max(rotations, 1);
@@ -523,7 +571,8 @@ public final class ChatScene implements EventListener, Restorable {
 		final var rotatableNodes = ReflectionUtil.getAllDeclaredNodeVariables(this);
 		for (final var node : rotatableNodes) {
 			// Sets the animation duration to {animationTime}
-			final var rotateTransition = new RotateTransition(Duration.seconds(animationTime), node);
+			final var rotateTransition =
+				new RotateTransition(Duration.seconds(animationTime), node);
 			// rotates every element {rotations} times
 			rotateTransition.setByAngle(rotations * 360);
 			rotateTransition.play();
@@ -534,9 +583,8 @@ public final class ChatScene implements EventListener, Restorable {
 	}
 
 	/**
-	 * Checks the text length of the {@code messageTextArea}, adjusts the
-	 * {@code remainingChars} label and checks whether to send the message
-	 * automatically.
+	 * Checks the text length of the {@code messageTextArea}, adjusts the {@code remainingChars}
+	 * label and checks whether to send the message automatically.
 	 *
 	 * @param e the key event that will be analyzed for a post request
 	 * @since Envoy Client v0.1-beta
@@ -549,29 +597,20 @@ public final class ChatScene implements EventListener, Restorable {
 
 		// Sending an IsTyping event if none has been sent for
 		// IsTyping#millisecondsActive
-		if (client.isOnline() && currentChat.getLastWritingEvent() + IsTyping.millisecondsActive <= System.currentTimeMillis()) {
-			client.send(new IsTyping(getChatID(), currentChat.getRecipient().getID()));
+		if (client.isOnline() && currentChat.getLastWritingEvent()
+			+ IsTyping.millisecondsActive <= System.currentTimeMillis()) {
+			client.send(new IsTyping(currentChat.getRecipient().getID()));
 			currentChat.lastWritingEventWasNow();
 		}
 
 		// KeyPressed will be called before the char has been added to the text, hence
 		// this is needed for the first char
-		if (messageTextArea.getText().length() == 1 && e != null) checkPostConditions(e);
+		if (messageTextArea.getText().length() == 1 && e != null)
+			checkPostConditions(e);
 
 		// This is needed for the messageTA context menu
-		else if (e == null) checkPostConditions(false);
-	}
-
-	/**
-	 * Returns the id that should be used to send things to the server: the id of
-	 * 'our' {@link User} if the recipient of that object is another User, else the
-	 * id of the {@link Group} 'our' user is sending to.
-	 *
-	 * @return an id that can be sent to the server
-	 * @since Envoy Client v0.2-beta
-	 */
-	private long getChatID() {
-		return currentChat.getRecipient() instanceof User ? client.getSender().getID() : currentChat.getRecipient().getID();
+		else if (e == null)
+			checkPostConditions(false);
 	}
 
 	/**
@@ -581,21 +620,25 @@ public final class ChatScene implements EventListener, Restorable {
 	@FXML
 	private void checkPostConditions(KeyEvent e) {
 		final var	enterPressed	= e.getCode() == KeyCode.ENTER;
-		final var	messagePosted	= enterPressed ? settings.isEnterToSend() ? !e.isControlDown() : e.isControlDown() : false;
+		final var	messagePosted	=
+			enterPressed ? settings.isEnterToSend() ? !e.isControlDown() : e.isControlDown()
+				: false;
 		if (messagePosted) {
 
 			// Removing an inserted line break if added by pressing enter
 			final var	text			= messageTextArea.getText();
 			final var	textPosition	= messageTextArea.getCaretPosition() - 1;
 			if (!e.isControlDown() && !text.isEmpty() && text.charAt(textPosition) == '\n')
-				messageTextArea.setText(new StringBuilder(text).deleteCharAt(textPosition).toString());
+				messageTextArea
+					.setText(new StringBuilder(text).deleteCharAt(textPosition).toString());
 		}
 
 		// if control is pressed, the enter press is originally invalidated. Here it'll
 		// be inserted again
 		else if (enterPressed && e.isControlDown()) {
 			var caretPosition = messageTextArea.getCaretPosition();
-			messageTextArea.setText(new StringBuilder(messageTextArea.getText()).insert(caretPosition, '\n').toString());
+			messageTextArea.setText(new StringBuilder(messageTextArea.getText())
+				.insert(caretPosition, '\n').toString());
 			messageTextArea.positionCaret(++caretPosition);
 		}
 		checkPostConditions(messagePosted);
@@ -603,8 +646,10 @@ public final class ChatScene implements EventListener, Restorable {
 
 	private void checkPostConditions(boolean postMessage) {
 		if (!postingPermanentlyDisabled) {
-			if (!postButton.isDisabled() && postMessage) postMessage();
-			postButton.setDisable(messageTextArea.getText().isBlank() && pendingAttachment == null || currentChat == null);
+			if (!postButton.isDisabled() && postMessage)
+				postMessage();
+			postButton.setDisable(messageTextArea.getText().isBlank() && pendingAttachment == null
+				|| currentChat == null);
 		} else {
 			final var noMoreMessaging = "Go online to send messages";
 			if (!infoLabel.getText().equals(noMoreMessaging))
@@ -638,13 +683,14 @@ public final class ChatScene implements EventListener, Restorable {
 	private void updateRemainingCharsLabel() {
 		final var	currentLength	= messageTextArea.getText().length();
 		final var	remainingLength	= MAX_MESSAGE_LENGTH - currentLength;
-		remainingChars.setText(String.format("remaining chars: %d/%d", remainingLength, MAX_MESSAGE_LENGTH));
+		remainingChars
+			.setText(String.format("remaining chars: %d/%d", remainingLength, MAX_MESSAGE_LENGTH));
 		remainingChars.setTextFill(Color.rgb(currentLength, remainingLength, 0, 1));
 	}
 
 	/**
-	 * Sends a new {@link Message} or {@link GroupMessage} to the server based on
-	 * the text entered in the {@code messageTextArea} and the given attachment.
+	 * Sends a new {@link Message} or {@link GroupMessage} to the server based on the text entered
+	 * in the {@code messageTextArea} and the given attachment.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -659,9 +705,10 @@ public final class ChatScene implements EventListener, Restorable {
 			return;
 		}
 		final var text = messageTextArea.getText().strip();
-		if (!messageTextAreaCommands.executeIfAnyPresent(text)) {
+		if (!commands.getChatSceneCommands().executeIfPresent(text)) {
 			// Creating the message and its metadata
-			final var builder = new MessageBuilder(localDB.getUser().getID(), currentChat.getRecipient().getID(), localDB.getIDGenerator())
+			final var builder = new MessageBuilder(localDB.getUser().getID(),
+				currentChat.getRecipient().getID(), localDB.getIDGenerator())
 					.setText(text);
 			// Setting an attachment, if present
 			if (pendingAttachment != null) {
@@ -670,7 +717,8 @@ public final class ChatScene implements EventListener, Restorable {
 				updateAttachmentView(false);
 			}
 			// Building the final message
-			final var message = currentChat.getRecipient() instanceof Group ? builder.buildGroupMessage((Group) currentChat.getRecipient())
+			final var message = currentChat.getRecipient() instanceof Group
+				? builder.buildGroupMessage((Group) currentChat.getRecipient())
 				: builder.build();
 
 			// Send message
@@ -682,14 +730,15 @@ public final class ChatScene implements EventListener, Restorable {
 			Platform.runLater(() -> {
 				chats.getSource().remove(currentChat);
 				((ObservableList<Chat>) chats.getSource()).add(0, currentChat);
-				chatList.getSelectionModel().select(0);
 				localDB.getChats().remove(currentChat);
 				localDB.getChats().add(0, currentChat);
+				chatList.getSelectionModel().select(0);
 			});
 			scrollToMessageListEnd();
 
 			// Request a new ID generator if all IDs were used
-			if (!localDB.getIDGenerator().hasNext() && client.isOnline()) client.requestIDGenerator();
+			if (!localDB.getIDGenerator().hasNext() && client.isOnline())
+				client.requestIDGenerator();
 		}
 
 		// Clear text field and disable post button
@@ -704,14 +753,16 @@ public final class ChatScene implements EventListener, Restorable {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	private void scrollToMessageListEnd() { messageList.scrollTo(messageList.getItems().size() - 1); }
+	private void scrollToMessageListEnd() {
+		messageList.scrollTo(messageList.getItems().size() - 1);
+	}
 
 	/**
 	 * Updates the {@code infoLabel}.
 	 *
 	 * @param text        the text to use
-	 * @param infoLabelID the id the the {@code infoLabel} should have so that it
-	 *                    can be styled accordingly in CSS
+	 * @param infoLabelID the id the the {@code infoLabel} should have so that it can be styled
+	 *                    accordingly in CSS
 	 * @since Envoy Client v0.1-beta
 	 */
 	private void updateInfoLabel(String text, String infoLabelID) {
@@ -722,26 +773,91 @@ public final class ChatScene implements EventListener, Restorable {
 
 	/**
 	 * Updates the {@code attachmentView} in terms of visibility.<br>
-	 * Additionally resets the shown image to {@code DEFAULT_ATTACHMENT_VIEW_IMAGE}
-	 * if another image is currently present.
+	 * Additionally resets the shown image to {@code DEFAULT_ATTACHMENT_VIEW_IMAGE} if another image
+	 * is currently present.
 	 *
 	 * @param visible whether the {@code attachmentView} should be displayed
 	 * @since Envoy Client v0.1-beta
 	 */
 	private void updateAttachmentView(boolean visible) {
-		if (!attachmentView.getImage().equals(DEFAULT_ATTACHMENT_VIEW_IMAGE)) attachmentView.setImage(DEFAULT_ATTACHMENT_VIEW_IMAGE);
+		if (!(attachmentView.getImage() == null
+			|| attachmentView.getImage().equals(DEFAULT_ATTACHMENT_VIEW_IMAGE)))
+			attachmentView.setImage(DEFAULT_ATTACHMENT_VIEW_IMAGE);
 		attachmentView.setVisible(visible);
 	}
 
-	// Context menu actions
+	@Event(OwnStatusChange.class)
+	@Priority(50)
+	private void generateOwnStatusControl() {
 
-	@FXML
-	private void deleteContact() { try {} catch (final NullPointerException e) {} }
+		// Update the own user status if present
+		if (ownContactControl.getChildren().get(1) instanceof ContactControl)
+			((ContactControl) ownContactControl.getChildren().get(1)).replaceInfoLabel();
+		else {
+
+			// Else prepend it to the HBox children
+			final var ownUserControl = new ContactControl(localDB.getUser());
+			ownUserControl.setAlignment(Pos.CENTER_LEFT);
+			HBox.setHgrow(ownUserControl, javafx.scene.layout.Priority.NEVER);
+			ownContactControl.getChildren().add(1, ownUserControl);
+		}
+	}
+
+	/**
+	 * Redesigns the UI when the {@link Chat} of the given contact has been marked as disabled.
+	 *
+	 * @param event the contact whose chat got disabled
+	 * @since Envoy Client v0.3-beta
+	 */
+	@Event
+	public void disableChat(ContactDisabled event) {
+		chatList.refresh();
+		final var recipient = event.get();
+
+		// Decrement member count for groups
+		if (recipient instanceof Group)
+			topBarStatusLabel.setText(recipient.getContacts().size() + " member"
+				+ (recipient.getContacts().size() != 1 ? "s" : ""));
+		if (currentChat != null && currentChat.getRecipient().equals(recipient)) {
+			messageTextArea.setDisable(true);
+			voiceButton.setDisable(true);
+			attachmentButton.setDisable(true);
+			pendingAttachment = null;
+			messageList.getStyleClass().clear();
+			messageList.getStyleClass().add("disabled-chat");
+		}
+	}
+
+	/**
+	 * Resets every component back to its inital state before a chat was selected.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void resetState() {
+		currentChat = null;
+		chatList.getSelectionModel().clearSelection();
+		messageList.getItems().clear();
+		messageTextArea.setDisable(true);
+		attachmentView.setImage(null);
+		topBarContactLabel.setVisible(false);
+		topBarStatusLabel.setVisible(false);
+		messageSearchButton.setVisible(false);
+		messageTextArea.clear();
+		messageTextArea.setDisable(true);
+		attachmentButton.setDisable(true);
+		voiceButton.setDisable(true);
+		remainingChars.setVisible(false);
+		pendingAttachment = null;
+		recipientProfilePic.setImage(null);
+		if (recorder.isRecording())
+			recorder.cancel();
+	}
 
 	@FXML
 	private void copyAndPostMessage() {
 		final var messageText = messageTextArea.getText();
-		Toolkit.getDefaultToolkit().getSystemClipboard().setContents(new StringSelection(messageText), null);
+		Toolkit.getDefaultToolkit().getSystemClipboard()
+			.setContents(new StringSelection(messageText), null);
 		final var	image				= attachmentView.getImage();
 		final var	messageAttachment	= pendingAttachment;
 		postMessage();
@@ -749,13 +865,45 @@ public final class ChatScene implements EventListener, Restorable {
 		updateRemainingCharsLabel();
 		postButton.setDisable(messageText.isBlank());
 		attachmentView.setImage(image);
-		if (attachmentView.getImage() != null) attachmentView.setVisible(true);
+		if (attachmentView.getImage() != null)
+			attachmentView.setVisible(true);
 		pendingAttachment = messageAttachment;
 	}
 
+	/**
+	 * Clears the current message selection.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void clearMessageSelection() {
+		messageList.getSelectionModel().clearSelection();
+	}
+
 	@FXML
 	private void searchContacts() {
 		chats.setPredicate(contactSearch.getText().isBlank() ? c -> true
-				: c -> c.getRecipient().getName().toLowerCase().contains(contactSearch.getText().toLowerCase()));
+			: c -> c.getRecipient().getName().toLowerCase()
+				.contains(contactSearch.getText().toLowerCase()));
+	}
+
+	@Override
+	public Map<KeyCombination, Runnable> getKeyboardShortcuts() {
+		return Map.<KeyCombination, Runnable>of(
+
+			// Delete text before the caret with "Control" + U
+			new KeyCodeCombination(KeyCode.U, KeyCombination.CONTROL_DOWN), () -> {
+				messageTextArea
+					.setText(
+						messageTextArea.getText().substring(messageTextArea.getCaretPosition()));
+				checkPostConditions(false);
+
+				// Delete text after the caret with "Control" + K
+			}, new KeyCodeCombination(KeyCode.K, KeyCombination.CONTROL_DOWN), () -> {
+				messageTextArea
+					.setText(
+						messageTextArea.getText().substring(0, messageTextArea.getCaretPosition()));
+				checkPostConditions(false);
+				messageTextArea.positionCaret(messageTextArea.getText().length());
+			});
 	}
 }

client/src/main/java/envoy/client/ui/controller/ContactSearchTab.java

@@ -7,34 +7,34 @@ import javafx.fxml.FXML;
 import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 
+import dev.kske.eventbus.core.*;
+
+import envoy.data.User;
+import envoy.event.ElementOperation;
+import envoy.event.contact.*;
+import envoy.util.EnvoyLog;
+
 import envoy.client.data.Context;
 import envoy.client.event.BackEvent;
 import envoy.client.helper.AlertHelper;
 import envoy.client.net.Client;
 import envoy.client.ui.control.ContactControl;
 import envoy.client.ui.listcell.ListCellFactory;
-import envoy.data.User;
-import envoy.event.ElementOperation;
-import envoy.event.contact.*;
-import envoy.util.EnvoyLog;
-
-import dev.kske.eventbus.*;
 
 /**
- * Provides a search bar in which a user name (substring) can be entered. The
- * users with a matching name are then displayed inside a list view. A
- * {@link UserSearchRequest} is sent on every keystroke.
+ * Provides a search bar in which a user name (substring) can be entered. The users with a matching
+ * name are then displayed inside a list view. A {@link UserSearchRequest} is sent on every
+ * keystroke.
  * <p>
  * <i>The actual search algorithm is implemented on the server.
  * <p>
- * To create a group, a button is available that loads the
- * {@link GroupCreationTab}.
+ * To create a group, a button is available that loads the {@link GroupCreationTab}.
  *
  * @author Leon Hofmeister
  * @author Maximilian K&auml;fer
  * @since Envoy Client v0.1-beta
  */
-public class ContactSearchTab implements EventListener {
+public class ContactSearchTab {
 
 	@FXML
 	private TextArea searchBar;
@@ -59,15 +59,21 @@ public class ContactSearchTab implements EventListener {
 
 	@Event
 	private void onUserSearchResult(UserSearchResult result) {
-		Platform.runLater(() -> { userList.getItems().clear(); userList.getItems().addAll(result.get()); });
+		Platform.runLater(() -> {
+			userList.getItems().clear();
+			userList.getItems().addAll(result.get());
+		});
 	}
 
 	@Event
-	private void onContactOperation(ContactOperation operation) {
+	private void onUserOperation(UserOperation operation) {
 		final var contact = operation.get();
-		if (operation.getOperationType() == ElementOperation.ADD) Platform.runLater(() -> {
+		if (operation.getOperationType() == ElementOperation.ADD)
+			Platform.runLater(() -> {
 				userList.getItems().remove(contact);
-			if (currentlySelectedUser != null && currentlySelectedUser.equals(contact) && alert.isShowing()) alert.close();
+				if (currentlySelectedUser != null && currentlySelectedUser.equals(contact)
+					&& alert.isShowing())
+					alert.close();
 			});
 	}
 
@@ -79,13 +85,15 @@ public class ContactSearchTab implements EventListener {
 	@FXML
 	private void sendRequest() {
 		final var text = searchBar.getText().strip();
-		if (!text.isBlank()) client.send(new UserSearchRequest(text));
-		else userList.getItems().clear();
+		if (!text.isBlank())
+			client.send(new UserSearchRequest(text));
+		else
+			userList.getItems().clear();
 	}
 
 	/**
-	 * Clears the text in the search bar and the items shown in the list.
-	 * Additionally disables both clear and search button.
+	 * Clears the text in the search bar and the items shown in the list. Additionally disables both
+	 * clear and search button.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -96,8 +104,7 @@ public class ContactSearchTab implements EventListener {
 	}
 
 	/**
-	 * Sends an {@link ContactOperation} for the selected user to the
-	 * server.
+	 * Sends an {@link UserOperation} for the selected user to the server.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -106,7 +113,8 @@ public class ContactSearchTab implements EventListener {
 		final var user = userList.getSelectionModel().getSelectedItem();
 		if (user != null) {
 			currentlySelectedUser = user;
-			alert.setContentText("Add user " + currentlySelectedUser.getName() + " to your contacts?");
+			alert.setContentText(
+				"Add user " + currentlySelectedUser.getName() + " to your contacts?");
 			AlertHelper.confirmAction(alert, this::addAsContact);
 		}
 	}
@@ -114,7 +122,7 @@ public class ContactSearchTab implements EventListener {
 	private void addAsContact() {
 
 		// Sends the event to the server
-		final var event = new ContactOperation(currentlySelectedUser, ElementOperation.ADD);
+		final var event = new UserOperation(currentlySelectedUser, ElementOperation.ADD);
 		client.send(event);
 
 		// Removes the chosen user and updates the UI
@@ -124,5 +132,8 @@ public class ContactSearchTab implements EventListener {
 	}
 
 	@FXML
-	private void backButtonClicked() { eventBus.dispatch(new BackEvent()); }
+	private void backButtonClicked() {
+		searchBar.setText("");
+		eventBus.dispatch(new BackEvent());
+	}
 }

client/src/main/java/envoy/client/ui/controller/GroupCreationTab.java

@@ -7,32 +7,33 @@ import java.util.stream.Collectors;
 import javafx.application.Platform;
 import javafx.fxml.FXML;
 import javafx.scene.control.*;
+import javafx.scene.input.MouseEvent;
 import javafx.scene.layout.HBox;
 
-import envoy.client.data.*;
-import envoy.client.event.BackEvent;
-import envoy.client.ui.control.ContactControl;
-import envoy.client.ui.listcell.ListCellFactory;
+import dev.kske.eventbus.core.*;
+
 import envoy.data.*;
 import envoy.event.GroupCreation;
-import envoy.event.contact.ContactOperation;
+import envoy.event.contact.UserOperation;
 import envoy.util.Bounds;
 
-import dev.kske.eventbus.*;
+import envoy.client.data.*;
+import envoy.client.event.*;
+import envoy.client.ui.control.*;
+import envoy.client.ui.listcell.ListCellFactory;
 
 /**
- * Provides a group creation interface. A group name can be entered in the text
- * field at the top. Available users (local chat recipients) are displayed
- * inside a list and can be selected (multiple selection available).
+ * Provides a group creation interface. A group name can be entered in the text field at the top.
+ * Available users (local chat recipients) are displayed inside a list and can be selected (multiple
+ * selection available).
  * <p>
- * When the group creation button is pressed, a {@link GroupCreation} is sent to
- * the server. This controller enforces a valid group name and a non-empty
- * member list (excluding the client user).
+ * When the group creation button is pressed, a {@link GroupCreation} is sent to the server. This
+ * controller enforces a valid group name and a non-empty member list (excluding the client user).
  *
  * @author Maximilian K&auml;fer
  * @since Envoy Client v0.1-beta
  */
-public class GroupCreationTab implements EventListener {
+public class GroupCreationTab {
 
 	@FXML
 	private Button createButton;
@@ -58,6 +59,9 @@ public class GroupCreationTab implements EventListener {
 	@FXML
 	private HBox errorProceedBox;
 
+	@FXML
+	private ListView<QuickSelectControl> quickSelectList;
+
 	private String name;
 
 	private final LocalDB localDB = Context.getInstance().getLocalDB();
@@ -67,7 +71,6 @@ public class GroupCreationTab implements EventListener {
 	@FXML
 	private void initialize() {
 		userList.setCellFactory(new ListCellFactory<>(ContactControl::new));
-		userList.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
 		createButton.setDisable(true);
 		eventBus.registerListener(this);
 		userList.getItems()
@@ -78,6 +81,8 @@ public class GroupCreationTab implements EventListener {
 				.filter(not(localDB.getUser()::equals))
 				.map(User.class::cast)
 				.collect(Collectors.toList()));
+		resizeQuickSelectSpace(0);
+		quickSelectList.addEventFilter(MouseEvent.MOUSE_PRESSED, MouseEvent::consume);
 	}
 
 	/**
@@ -86,16 +91,29 @@ public class GroupCreationTab implements EventListener {
 	 * @since Envoy Client v0.1-beta
 	 */
 	@FXML
-	private void userListClicked() { createButton.setDisable(userList.getSelectionModel().isEmpty() || groupNameField.getText().isBlank()); }
+	private void userListClicked() {
+		if (userList.getSelectionModel().getSelectedItem() != null) {
+			quickSelectList.getItems().add(new QuickSelectControl(
+				userList.getSelectionModel().getSelectedItem(), this::removeFromQuickSelection));
+			createButton.setDisable(
+				quickSelectList.getItems().isEmpty() || groupNameField.getText().isBlank());
+			resizeQuickSelectSpace(60);
+			userList.getItems().remove(userList.getSelectionModel().getSelectedItem());
+			userList.getSelectionModel().clearSelection();
+		}
+	}
 
 	/**
-	 * Checks, whether the {@code createButton} can be enabled because text is
-	 * present in the text field.
+	 * Checks, whether the {@code createButton} can be enabled because text is present in the text
+	 * field.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
 	@FXML
-	private void textUpdated() { createButton.setDisable(userList.getSelectionModel().isEmpty() || groupNameField.getText().isBlank()); }
+	private void textUpdated() {
+		createButton
+			.setDisable(quickSelectList.getItems().isEmpty() || groupNameField.getText().isBlank());
+	}
 
 	/**
 	 * Sends a {@link GroupCreation} to the server and closes this scene.
@@ -123,6 +141,9 @@ public class GroupCreationTab implements EventListener {
 			// Restoring the original design as tabs will always be reused
 			setErrorMessageLabelSize(0);
 			groupNameField.clear();
+			quickSelectList.getItems().forEach(q -> userList.getItems().add(q.getUser()));
+			quickSelectList.getItems().clear();
+			resizeQuickSelectSpace(0);
 		}
 	}
 
@@ -136,19 +157,41 @@ public class GroupCreationTab implements EventListener {
 	private void createGroup(String name) {
 		Context.getInstance()
 			.getClient()
-			.send(new GroupCreation(name, userList.getSelectionModel().getSelectedItems().stream().map(User::getID).collect(Collectors.toSet())));
+			.send(new GroupCreation(name, quickSelectList.getItems().stream()
+				.map(q -> q.getUser().getID()).collect(Collectors.toSet())));
 	}
 
 	/**
-	 * Returns true if the proposed group name is already present in the users
-	 * {@code LocalDB}.
+	 * Returns true if the proposed group name is already present in the users {@code LocalDB}.
 	 *
 	 * @param newName the chosen group name
 	 * @return true if this name is already present
 	 * @since Envoy Client v0.1-beta
 	 */
 	public boolean groupNameAlreadyPresent(String newName) {
-		return localDB.getChats().stream().map(Chat::getRecipient).filter(Group.class::isInstance).map(Contact::getName).anyMatch(newName::equals);
+		return localDB.getChats().stream().map(Chat::getRecipient).filter(Group.class::isInstance)
+			.map(Contact::getName).anyMatch(newName::equals);
+	}
+
+	/**
+	 * Removes an element from the quickSelectList.
+	 *
+	 * @param element the element to be removed.
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void removeFromQuickSelection(QuickSelectControl element) {
+		quickSelectList.getItems().remove(element);
+		userList.getItems().add(element.getUser());
+		if (quickSelectList.getItems().isEmpty()) {
+			resizeQuickSelectSpace(0);
+			createButton.setDisable(true);
+		}
+	}
+
+	private void resizeQuickSelectSpace(int value) {
+		quickSelectList.setPrefHeight(value);
+		quickSelectList.setMaxHeight(value);
+		quickSelectList.setMinHeight(value);
 	}
 
 	@FXML
@@ -197,11 +240,11 @@ public class GroupCreationTab implements EventListener {
 	}
 
 	@Event
-	private void onContactOperation(ContactOperation operation) {
-		if (operation.get() instanceof User) Platform.runLater(() -> {
+	private void onUserOperation(UserOperation operation) {
+		Platform.runLater(() -> {
 			switch (operation.getOperationType()) {
 				case ADD:
-					userList.getItems().add((User) operation.get());
+					userList.getItems().add(operation.get());
 					break;
 				case REMOVE:
 					userList.getItems().removeIf(operation.get()::equals);
@@ -209,4 +252,10 @@ public class GroupCreationTab implements EventListener {
 			}
 		});
 	}
+
+	@Event
+	private void onAccountDeletion(AccountDeletion deletion) {
+		final var deletedID = deletion.get();
+		Platform.runLater(() -> userList.getItems().removeIf(user -> (user.getID() == deletedID)));
+	}
 }

client/src/main/java/envoy/client/ui/controller/LoginScene.java

@@ -10,14 +10,15 @@ import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 import javafx.scene.image.ImageView;
 
-import envoy.client.data.ClientConfig;
-import envoy.client.ui.*;
-import envoy.client.util.IconUtil;
+import dev.kske.eventbus.core.*;
+
 import envoy.data.LoginCredentials;
 import envoy.event.HandshakeRejection;
 import envoy.util.*;
 
-import dev.kske.eventbus.*;
+import envoy.client.data.ClientConfig;
+import envoy.client.ui.Startup;
+import envoy.client.util.IconUtil;
 
 /**
  * Controller for the login scene.
@@ -26,7 +27,7 @@ import dev.kske.eventbus.*;
  * @author Maximilian Käfer
  * @since Envoy Client v0.1-beta
  */
-public final class LoginScene implements EventListener {
+public final class LoginScene {
 
 	@FXML
 	private TextField userTextField;
@@ -78,25 +79,32 @@ public final class LoginScene implements EventListener {
 
 	@FXML
 	private void loginButtonPressed() {
-		final String user = userTextField.getText(), pass = passwordField.getText(), repeatPass = repeatPasswordField.getText();
+		final String	user			= userTextField.getText(), pass = passwordField.getText(),
+			repeatPass = repeatPasswordField.getText();
 		final boolean	requestToken	= cbStaySignedIn.isSelected();
 
 		// Prevent registration with unequal passwords
 		if (registration && !pass.equals(repeatPass)) {
-			new Alert(AlertType.ERROR, "The entered password is unequal to the repeated one").showAndWait();
+			new Alert(AlertType.ERROR, "The entered password is unequal to the repeated one")
+				.showAndWait();
 			repeatPasswordField.clear();
 		} else if (!Bounds.isValidContactName(user)) {
-			new Alert(AlertType.ERROR, "The entered user name is not valid (" + Bounds.CONTACT_NAME_PATTERN + ")").showAndWait();
+			new Alert(AlertType.ERROR,
+				"The entered user name is not valid (" + Bounds.CONTACT_NAME_PATTERN + ")")
+					.showAndWait();
 			userTextField.clear();
 		} else {
 			Instant lastSync = Startup.loadLastSync(userTextField.getText());
-			Startup.performHandshake(registration ? LoginCredentials.registration(user, pass, requestToken, Startup.VERSION, lastSync)
+			Startup.performHandshake(registration
+				? LoginCredentials.registration(user, pass, requestToken, Startup.VERSION, lastSync)
 				: LoginCredentials.login(user, pass, requestToken, Startup.VERSION, lastSync));
 		}
 	}
 
 	@FXML
-	private void offlineModeButtonPressed() { Startup.attemptOfflineMode(userTextField.getText()); }
+	private void offlineModeButtonPressed() {
+		Startup.attemptOfflineMode(userTextField.getText());
+	}
 
 	@FXML
 	private void registerSwitchPressed() {
@@ -127,5 +135,7 @@ public final class LoginScene implements EventListener {
 	}
 
 	@Event
-	private void onHandshakeRejection(HandshakeRejection evt) { Platform.runLater(() -> new Alert(AlertType.ERROR, evt.get()).showAndWait()); }
+	private void onHandshakeRejection(HandshakeRejection evt) {
+		Platform.runLater(() -> new Alert(AlertType.ERROR, evt.get()).showAndWait());
+	}
 }

client/src/main/java/envoy/client/ui/controller/SettingsScene.java

@@ -1,9 +1,13 @@
 package envoy.client.ui.controller;
 
+import java.util.Map;
+
 import javafx.fxml.FXML;
 import javafx.scene.control.*;
+import javafx.scene.input.*;
 
 import envoy.client.data.Context;
+import envoy.client.data.shortcuts.KeyboardMapping;
 import envoy.client.ui.listcell.ListCellFactory;
 import envoy.client.ui.settings.*;
 
@@ -13,7 +17,7 @@ import envoy.client.ui.settings.*;
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
  */
-public final class SettingsScene {
+public final class SettingsScene implements KeyboardMapping {
 
 	@FXML
 	private ListView<SettingsPane> settingsList;
@@ -24,7 +28,8 @@ public final class SettingsScene {
 	@FXML
 	private void initialize() {
 		settingsList.setCellFactory(new ListCellFactory<>(pane -> new Label(pane.getTitle())));
-		settingsList.getItems().addAll(new GeneralSettingsPane(), new UserSettingsPane(), new DownloadSettingsPane(), new BugReportPane());
+		settingsList.getItems().addAll(new GeneralSettingsPane(), new UserSettingsPane(),
+			new DownloadSettingsPane(), new BugReportPane());
 	}
 
 	@FXML
@@ -37,5 +42,13 @@ public final class SettingsScene {
 	}
 
 	@FXML
-	private void backButtonClicked() { Context.getInstance().getSceneContext().pop(); }
+	private void backButtonClicked() {
+		Context.getInstance().getSceneContext().pop();
+	}
+
+	@Override
+	public Map<KeyCombination, Runnable> getKeyboardShortcuts() {
+		return Map.of(new KeyCodeCombination(KeyCode.B, KeyCombination.CONTROL_DOWN),
+			this::backButtonClicked);
+	}
 }

client/src/main/java/envoy/client/ui/listcell/AbstractListCell.java

@@ -33,6 +33,7 @@ public abstract class AbstractListCell<T, U extends Node> extends ListCell<T> {
 			setGraphic(renderItem(item));
 		} else {
 			setGraphic(null);
+			setCursor(Cursor.DEFAULT);
 		}
 	}
 

client/src/main/java/envoy/client/ui/listcell/ChatListCell.java

@@ -0,0 +1,55 @@
+package envoy.client.ui.listcell;
+
+import javafx.scene.control.*;
+
+import envoy.data.User;
+
+import envoy.client.data.*;
+import envoy.client.net.Client;
+import envoy.client.ui.control.ChatControl;
+import envoy.client.util.UserUtil;
+
+/**
+ * A list cell containing chats represented as chat controls.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public class ChatListCell extends AbstractListCell<Chat, ChatControl> {
+
+	private static final Client client = Context.getInstance().getClient();
+
+	/**
+	 * @param listView the list view inside of which the cell will be displayed
+	 * @since Envoy Client v0.3-beta
+	 */
+	public ChatListCell(ListView<? extends Chat> listView) {
+		super(listView);
+	}
+
+	@Override
+	protected ChatControl renderItem(Chat chat) {
+		if (client.isOnline()) {
+			final var	menu		= new ContextMenu();
+			final var	removeMI	= new MenuItem();
+			removeMI.setText(
+				chat.isDisabled() ? "Delete "
+					: chat.getRecipient() instanceof User ? "Block "
+						: "Leave group " + chat.getRecipient().getName());
+			removeMI.setOnAction(
+				chat.isDisabled() ? e -> UserUtil.deleteContact(chat.getRecipient())
+					: e -> UserUtil.disableContact(chat.getRecipient()));
+			menu.getItems().add(removeMI);
+			setContextMenu(menu);
+		} else
+			setContextMenu(null);
+
+		// TODO: replace with icon in ChatControl
+		final var chatControl = new ChatControl(chat);
+		if (chat.isDisabled())
+			chatControl.getStyleClass().add("disabled-chat");
+		else
+			chatControl.getStyleClass().remove("disabled-chat");
+		return chatControl;
+	}
+}

client/src/main/java/envoy/client/ui/listcell/GenericListCell.java

@@ -28,5 +28,7 @@ public final class GenericListCell<T, U extends Node> extends AbstractListCell<T
 	}
 
 	@Override
-	protected U renderItem(T item) { return renderer.apply(item); }
+	protected U renderItem(T item) {
+		return renderer.apply(item);
+	}
 }

client/src/main/java/envoy/client/ui/listcell/ListCellFactory.java

@@ -7,15 +7,15 @@ import javafx.scene.control.*;
 import javafx.util.Callback;
 
 /**
- * Provides a creation mechanism for generic list cells given a list view and a
- * conversion function.
+ * Provides a creation mechanism for generic list cells given a list view and a conversion function.
  *
  * @author Kai S. K. Engelbart
  * @param <T> the type of object to display
  * @param <U> the type of node displayed
  * @since Envoy Client v0.1-beta
  */
-public final class ListCellFactory<T, U extends Node> implements Callback<ListView<T>, ListCell<T>> {
+public final class ListCellFactory<T, U extends Node>
+	implements Callback<ListView<T>, ListCell<T>> {
 
 	private final Function<? super T, U> renderer;
 
@@ -23,8 +23,12 @@ public final class ListCellFactory<T, U extends Node> implements Callback<ListVi
 	 * @param renderer a function converting the type to display into a node
 	 * @since Envoy Client v0.1-beta
 	 */
-	public ListCellFactory(Function<? super T, U> renderer) { this.renderer = renderer; }
+	public ListCellFactory(Function<? super T, U> renderer) {
+		this.renderer = renderer;
+	}
 
 	@Override
-	public ListCell<T> call(ListView<T> listView) { return new GenericListCell<>(listView, renderer); }
+	public ListCell<T> call(ListView<T> listView) {
+		return new GenericListCell<>(listView, renderer);
+	}
 }

client/src/main/java/envoy/client/ui/listcell/MessageListCell.java

@@ -3,9 +3,10 @@ package envoy.client.ui.listcell;
 import javafx.geometry.*;
 import javafx.scene.control.ListView;
 
-import envoy.client.ui.control.MessageControl;
 import envoy.data.Message;
 
+import envoy.client.ui.control.MessageControl;
+
 /**
  * A list cell containing messages represented as message controls.
  *
@@ -18,20 +19,25 @@ public final class MessageListCell extends AbstractListCell<Message, MessageCont
 	 * @param listView the list view inside of which the cell will be displayed
 	 * @since Envoy Client v0.1-beta
 	 */
-	public MessageListCell(ListView<? extends Message> listView) { super(listView); }
+	public MessageListCell(ListView<? extends Message> listView) {
+		super(listView);
+	}
 
 	@Override
 	protected MessageControl renderItem(Message message) {
 		final var control = new MessageControl(message);
-		listView.widthProperty().addListener((observable, oldValue, newValue) -> adjustPadding(newValue.intValue(), control.isOwnMessage()));
+		listView.widthProperty().addListener((observable, oldValue,
+			newValue) -> adjustPadding(newValue.intValue(), control.isOwnMessage()));
 		adjustPadding((int) listView.getWidth(), control.isOwnMessage());
-		if (control.isOwnMessage()) setAlignment(Pos.CENTER_RIGHT);
-		else setAlignment(Pos.CENTER_LEFT);
+		if (control.isOwnMessage())
+			setAlignment(Pos.CENTER_RIGHT);
+		else
+			setAlignment(Pos.CENTER_LEFT);
 		return control;
 	}
 
 	private void adjustPadding(int listWidth, boolean ownMessage) {
 		int padding = 10 + Math.max((listWidth - 1000) / 2, 0);
-		setPadding(ownMessage ? new Insets(0, padding, 6, 0) : new Insets(0, 0, 6, padding));
+		setPadding(ownMessage ? new Insets(3, padding, 3, 0) : new Insets(3, 0, 3, padding));
 	}
 }

client/src/main/java/envoy/client/ui/listcell/package-info.java

@@ -1,6 +1,5 @@
 /**
- * This package contains custom list cells that are used to display certain
- * things.
+ * This package contains custom list cells that are used to display certain things.
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart

client/src/main/java/envoy/client/ui/settings/BugReportPane.java

@@ -7,8 +7,8 @@ import javafx.scene.input.InputEvent;
 import envoy.event.IssueProposal;
 
 /**
- * This class offers the option for users to submit a bug report. Only the title
- * of a bug is needed to be sent.
+ * This class offers the option for users to submit a bug report. Only the title of a bug is needed
+ * to be sent.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
@@ -17,12 +17,15 @@ public final class BugReportPane extends OnlineOnlySettingsPane {
 
 	private final Label		titleLabel				= new Label("Suggest a title for the bug:");
 	private final TextField	titleTextField			= new TextField();
-	private final Label		pleaseExplainLabel		= new Label("Paste here the log of what went wrong and/ or explain what went wrong:");
+	private final Label		pleaseExplainLabel		=
+		new Label("Paste here the log of what went wrong and/ or explain what went wrong:");
 	private final TextArea	errorDetailArea			= new TextArea();
-	private final CheckBox	showUsernameInBugReport	= new CheckBox("Show your username in the bug report?");
+	private final CheckBox	showUsernameInBugReport	=
+		new CheckBox("Show your username in the bug report?");
 	private final Button	submitReportButton		= new Button("Submit report");
 
-	private final EventHandler<? super InputEvent> inputEventHandler = e -> submitReportButton.setDisable(titleTextField.getText().isBlank());
+	private final EventHandler<? super InputEvent> inputEventHandler =
+		e -> submitReportButton.setDisable(titleTextField.getText().isBlank());
 
 	/**
 	 * Creates a new {@code BugReportPane}.
@@ -59,7 +62,9 @@ public final class BugReportPane extends OnlineOnlySettingsPane {
 		submitReportButton.setDisable(true);
 		submitReportButton.setOnAction(e -> {
 			String title = titleTextField.getText(), description = errorDetailArea.getText();
-			client.send(showUsernameInBugReport.isSelected() ? new IssueProposal(title, description, true) : new IssueProposal(title, description, client.getSender().getName(), true));
+			client.send(
+				showUsernameInBugReport.isSelected() ? new IssueProposal(title, description, true)
+					: new IssueProposal(title, description, client.getSender().getName(), true));
 		});
 		getChildren().add(submitReportButton);
 	}

client/src/main/java/envoy/client/ui/settings/DownloadSettingsPane.java

@@ -5,8 +5,6 @@ import javafx.scene.control.*;
 import javafx.scene.layout.HBox;
 import javafx.stage.DirectoryChooser;
 
-import envoy.client.data.Context;
-
 /**
  * Displays options for downloading {@link envoy.data.Attachment}s.
  *
@@ -26,18 +24,22 @@ public final class DownloadSettingsPane extends SettingsPane {
 		setPadding(new Insets(15));
 
 		// Checkbox to disable asking
-		final var checkBox = new CheckBox(settings.getItems().get("autoSaveDownloads").getUserFriendlyName());
+		final var checkBox =
+			new CheckBox(settings.getItems().get("autoSaveDownloads").getUserFriendlyName());
 		checkBox.setSelected(settings.isDownloadSavedWithoutAsking());
-		checkBox.setTooltip(new Tooltip("Determines whether a \"Select save location\" - dialogue will be shown when saving attachments."));
+		checkBox.setTooltip(new Tooltip(
+			"Determines whether a \"Select save location\" - dialogue will be shown when saving attachments."));
 		checkBox.setOnAction(e -> settings.setDownloadSavedWithoutAsking(checkBox.isSelected()));
 		getChildren().add(checkBox);
 
 		// Displaying the default path to save to
-		final var pathLabel = new Label(settings.getItems().get("downloadLocation").getDescription() + ":");
+		final var pathLabel =
+			new Label(settings.getItems().get("downloadLocation").getDescription() + ":");
 		pathLabel.setWrapText(true);
 		getChildren().add(pathLabel);
 		final var hbox = new HBox(20);
-		Tooltip.install(hbox, new Tooltip("Determines the location where attachments will be saved to."));
+		Tooltip.install(hbox,
+			new Tooltip("Determines the location where attachments will be saved to."));
 		final var currentPath = new Label(settings.getDownloadLocation().getAbsolutePath());
 		hbox.getChildren().add(currentPath);
 
@@ -47,7 +49,8 @@ public final class DownloadSettingsPane extends SettingsPane {
 			final var directoryChooser = new DirectoryChooser();
 			directoryChooser.setTitle("Select the directory where attachments should be saved to");
 			directoryChooser.setInitialDirectory(settings.getDownloadLocation());
-			final var selectedDirectory = directoryChooser.showDialog(Context.getInstance().getSceneContext().getStage());
+			final var selectedDirectory =
+				directoryChooser.showDialog(context.getSceneContext().getStage());
 
 			if (selectedDirectory != null) {
 				currentPath.setText(selectedDirectory.getAbsolutePath());

client/src/main/java/envoy/client/ui/settings/GeneralSettingsPane.java

@@ -2,12 +2,14 @@ package envoy.client.ui.settings;
 
 import javafx.scene.control.*;
 
-import envoy.client.data.SettingsItem;
-import envoy.client.event.ThemeChangeEvent;
-import envoy.client.helper.ShutdownHelper;
+import dev.kske.eventbus.core.EventBus;
+
 import envoy.data.User.UserStatus;
 
-import dev.kske.eventbus.EventBus;
+import envoy.client.data.SettingsItem;
+import envoy.client.event.ThemeChangeEvent;
+import envoy.client.ui.StatusTrayIcon;
+import envoy.client.util.UserUtil;
 
 /**
  * @author Kai S. K. Engelbart
@@ -22,23 +24,31 @@ public final class GeneralSettingsPane extends SettingsPane {
 		super("General");
 		setSpacing(10);
 
-		// TODO: Support other value types
 		final var settingsItems = settings.getItems();
-		final var	hideOnCloseCheckbox	= new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("hideOnClose"));
-		final var	hideOnCloseTooltip	= new Tooltip("If selected, Envoy will still be present in the task bar when closed.");
+
+		// Add hide on close if supported
+		final var	hideOnCloseCheckbox	=
+			new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("hideOnClose"));
+		final var	hideOnCloseTooltip	= new Tooltip(StatusTrayIcon.isSupported()
+			? "If selected, Envoy will still be present in the task bar when closed."
+			: "status tray icon is not supported on your system.");
 		hideOnCloseTooltip.setWrapText(true);
 		hideOnCloseCheckbox.setTooltip(hideOnCloseTooltip);
+		hideOnCloseCheckbox.setDisable(!StatusTrayIcon.isSupported());
 		getChildren().add(hideOnCloseCheckbox);
 
-		final var	enterToSendCheckbox	= new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("enterToSend"));
+		final var	enterToSendCheckbox	=
+			new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("enterToSend"));
 		final var	enterToSendTooltip	= new Tooltip(
 			"When selected, messages can be sent pressing \"Enter\". A line break can be inserted by pressing \"Ctrl\" + \"Enter\". Else it will be the other way around.");
 		enterToSendTooltip.setWrapText(true);
 		enterToSendCheckbox.setTooltip(enterToSendTooltip);
 		getChildren().add(enterToSendCheckbox);
 
-		final var	askForConfirmationCheckbox	= new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("askForConfirmation"));
-		final var	askForConfirmationTooltip	= new Tooltip("When selected, nothing will prompt a confirmation dialog");
+		final var	askForConfirmationCheckbox	=
+			new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("askForConfirmation"));
+		final var	askForConfirmationTooltip	=
+			new Tooltip("When selected, nothing will prompt a confirmation dialog");
 		askForConfirmationTooltip.setWrapText(true);
 		askForConfirmationCheckbox.setTooltip(askForConfirmationTooltip);
 		getChildren().add(askForConfirmationCheckbox);
@@ -46,22 +56,26 @@ public final class GeneralSettingsPane extends SettingsPane {
 		final var combobox = new ComboBox<String>();
 		combobox.getItems().add("dark");
 		combobox.getItems().add("light");
-		combobox.setTooltip(new Tooltip("Determines the current theme Envoy will be displayed in."));
+		combobox
+			.setTooltip(new Tooltip("Determines the current theme Envoy will be displayed in."));
 		combobox.setValue(settings.getCurrentTheme());
-		combobox.setOnAction(e -> { settings.setCurrentTheme(combobox.getValue()); EventBus.getInstance().dispatch(new ThemeChangeEvent()); });
+		combobox.setOnAction(e -> {
+			settings.setCurrentTheme(combobox.getValue());
+			EventBus.getInstance().dispatch(new ThemeChangeEvent());
+		});
 		getChildren().add(combobox);
 
 		final var statusComboBox = new ComboBox<UserStatus>();
 		statusComboBox.getItems().setAll(UserStatus.values());
-		statusComboBox.setValue(UserStatus.ONLINE);
+		statusComboBox.setValue(context.getLocalDB().getUser().getStatus());
 		statusComboBox.setTooltip(new Tooltip("Change your current status"));
-		// TODO add action when value is changed
-		statusComboBox.setOnAction(e -> {});
+		statusComboBox.setOnAction(e -> UserUtil.changeStatus(statusComboBox.getValue()));
 		getChildren().add(statusComboBox);
 
 		final var logoutButton = new Button("Logout");
-		logoutButton.setOnAction(e -> ShutdownHelper.logout());
-		final var logoutTooltip = new Tooltip("Brings you back to the login screen and removes \"remember me\" status from this account");
+		logoutButton.setOnAction(e -> UserUtil.logout());
+		final var logoutTooltip = new Tooltip(
+			"Brings you back to the login screen and removes \"remember me\" status from this account");
 		logoutTooltip.setWrapText(true);
 		logoutButton.setTooltip(logoutTooltip);
 		getChildren().add(logoutButton);

client/src/main/java/envoy/client/ui/settings/OnlineOnlySettingsPane.java

@@ -5,14 +5,13 @@ import javafx.scene.control.*;
 import javafx.scene.layout.*;
 import javafx.scene.paint.Color;
 
-import envoy.client.data.Context;
 import envoy.client.net.Client;
 
 /**
- * Inheriting from this class signifies that options should only be available if
- * the {@link envoy.data.User} is currently online. If the user is currently
- * offline, all {@link javafx.scene.Node} variables will be disabled and a
- * {@link Tooltip} will be displayed for the whole node.
+ * Inheriting from this class signifies that options should only be available if the
+ * {@link envoy.data.User} is currently online. If the user is currently offline, all
+ * {@link javafx.scene.Node} variables will be disabled and a {@link Tooltip} will be displayed for
+ * the whole node.
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart
@@ -20,9 +19,10 @@ import envoy.client.net.Client;
  */
 public abstract class OnlineOnlySettingsPane extends SettingsPane {
 
-	protected final Client client = Context.getInstance().getClient();
+	protected final Client client = context.getClient();
 
-	private final Tooltip beOnlineReminder = new Tooltip("You need to be online to modify your account.");
+	private final Tooltip beOnlineReminder =
+		new Tooltip("You need to be online to modify your account.");
 
 	/**
 	 * @param title the title of this pane
@@ -34,14 +34,17 @@ public abstract class OnlineOnlySettingsPane extends SettingsPane {
 		setDisable(!client.isOnline());
 
 		if (!client.isOnline()) {
-			final var infoLabel = new Label("You shall not pass!\n(... Unless you would happen to be online)");
+			final var infoLabel =
+				new Label("You shall not pass!\n(... Unless you would happen to be online)");
 			infoLabel.setId("info-label-warning");
 			infoLabel.setWrapText(true);
 			getChildren().add(infoLabel);
-			setBackground(new Background(new BackgroundFill(Color.grayRgb(100, 0.3), CornerRadii.EMPTY, Insets.EMPTY)));
+			setBackground(new Background(
+				new BackgroundFill(Color.grayRgb(100, 0.3), CornerRadii.EMPTY, Insets.EMPTY)));
 
 			Tooltip.install(this, beOnlineReminder);
-		} else Tooltip.uninstall(this, beOnlineReminder);
+		} else
+			Tooltip.uninstall(this, beOnlineReminder);
 	}
 
 	/**
@@ -50,5 +53,7 @@ public abstract class OnlineOnlySettingsPane extends SettingsPane {
 	 * @param text the text to display
 	 * @since Envoy Client v0.2-beta
 	 */
-	protected void setToolTipText(String text) { beOnlineReminder.setText(text); }
+	protected void setToolTipText(String text) {
+		beOnlineReminder.setText(text);
+	}
 }

client/src/main/java/envoy/client/ui/settings/SettingsPane.java

@@ -2,7 +2,7 @@ package envoy.client.ui.settings;
 
 import javafx.scene.layout.VBox;
 
-import envoy.client.data.Settings;
+import envoy.client.data.*;
 
 /**
  * @author Kai S. K. Engelbart
@@ -13,8 +13,11 @@ public abstract class SettingsPane extends VBox {
 	protected String title;
 
 	protected static final Settings	settings	= Settings.getInstance();
+	protected static final Context	context		= Context.getInstance();
 
-	protected SettingsPane(String title) { this.title = title; }
+	protected SettingsPane(String title) {
+		this.title = title;
+	}
 
 	/**
 	 * @return the title of this settings pane

client/src/main/java/envoy/client/ui/settings/UserSettingsPane.java

@@ -13,14 +13,15 @@ import javafx.scene.image.*;
 import javafx.scene.input.InputEvent;
 import javafx.scene.layout.HBox;
 import javafx.stage.FileChooser;
+import javafx.util.Duration;
+
+import dev.kske.eventbus.core.EventBus;
 
-import envoy.client.data.Context;
-import envoy.client.ui.control.ProfilePicImageView;
-import envoy.client.util.IconUtil;
 import envoy.event.*;
 import envoy.util.*;
 
-import dev.kske.eventbus.EventBus;
+import envoy.client.ui.control.ProfilePicImageView;
+import envoy.client.util.*;
 
 /**
  * @author Leon Hofmeister
@@ -38,6 +39,7 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 	private final PasswordField	newPasswordField		= new PasswordField();
 	private final PasswordField	repeatNewPasswordField	= new PasswordField();
 	private final Button		saveButton				= new Button("Save");
+	private final Button		deleteAccountButton		= new Button("Delete Account (Locally)");
 
 	private static final EventBus	eventBus	= EventBus.getInstance();
 	private static final Logger		logger		= EnvoyLog.getLogger(UserSettingsPane.class);
@@ -59,21 +61,24 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 		profilePic.setFitWidth(60);
 		profilePic.setFitHeight(60);
 		profilePic.setOnMouseClicked(e -> {
-			if (!client.isOnline()) return;
+			if (!client.isOnline())
+				return;
 			final var pictureChooser = new FileChooser();
 
 			pictureChooser.setTitle("Select a new profile pic");
 			pictureChooser.setInitialDirectory(new File(System.getProperty("user.home")));
-			pictureChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("Pictures", "*.png", "*.jpg", "*.bmp", "*.gif"));
+			pictureChooser.getExtensionFilters().add(
+				new FileChooser.ExtensionFilter("Pictures", "*.png", "*.jpg", "*.bmp", "*.gif"));
 
-			final var file = pictureChooser.showOpenDialog(Context.getInstance().getSceneContext().getStage());
+			final var file = pictureChooser.showOpenDialog(context.getSceneContext().getStage());
 
 			if (file != null) {
 
 				// Check max file size
 				// TODO: Move to config
 				if (file.length() > 5E6) {
-					new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 5MB!").showAndWait();
+					new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 5MB!")
+						.showAndWait();
 					return;
 				}
 
@@ -103,14 +108,24 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 
 		// "Displaying" the password change mechanism
 		final HBox[]	passwordHBoxes	= { new HBox(), new HBox(), new HBox() };
-		final Label[]	passwordLabels	= { new Label("Enter current password:"), new Label("Enter new password:"),
+		final Label[]	passwordLabels	=
+			{	new Label("Enter current password:"), new Label("Enter new password:"),
 				new Label("Repeat new password:") };
 
-		final PasswordField[]					passwordFields	= { currentPasswordField, newPasswordField, repeatNewPasswordField };
-		final EventHandler<? super InputEvent>	passwordEntered	= e -> {
-																	newPassword		= newPasswordField.getText();
-																	validPassword	= newPassword.equals(repeatNewPasswordField.getText())
-																			&& !newPasswordField.getText().isBlank();
+		final PasswordField[]					passwordFields	=
+			{ currentPasswordField, newPasswordField, repeatNewPasswordField };
+		final EventHandler<? super InputEvent>	passwordEntered	=
+			e -> {
+																		newPassword	=
+																			newPasswordField
+																				.getText();
+																		validPassword =
+																			newPassword.equals(
+																				repeatNewPasswordField
+																					.getText())
+																				&& !newPasswordField
+																					.getText()
+																					.isBlank();
 																	};
 		newPasswordField.setOnInputMethodTextChanged(passwordEntered);
 		newPasswordField.setOnKeyTyped(passwordEntered);
@@ -126,9 +141,22 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 		}
 
 		// Displaying the save button
-		saveButton.setOnAction(e -> save(client.getSender().getID(), currentPasswordField.getText()));
+		saveButton
+			.setOnAction(e -> save(currentPasswordField.getText()));
 		saveButton.setAlignment(Pos.BOTTOM_RIGHT);
 		getChildren().add(saveButton);
+
+		// Displaying the delete account button
+		deleteAccountButton.setAlignment(Pos.BASELINE_CENTER);
+		deleteAccountButton.setOnAction(e -> UserUtil.deleteAccount());
+		deleteAccountButton.setText("Delete Account (locally)");
+		deleteAccountButton.setPrefHeight(25);
+		deleteAccountButton.getStyleClass().clear();
+		deleteAccountButton.getStyleClass().add("danger-button");
+		final var tooltip = new Tooltip("Remote deletion is currently unsupported.");
+		tooltip.setShowDelay(Duration.millis(100));
+		deleteAccountButton.setTooltip(tooltip);
+		getChildren().add(deleteAccountButton);
 	}
 
 	/**
@@ -137,11 +165,11 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 	 * @param username the new username
 	 * @since Envoy Client v0.2-beta
 	 */
-	private void save(long userID, String oldPassword) {
+	private void save(String oldPassword) {
 
 		// The profile pic was changed
 		if (profilePicChanged) {
-			final var profilePicChangeEvent = new ProfilePicChange(currentImageBytes, userID);
+			final var profilePicChangeEvent = new ProfilePicChange(currentImageBytes);
 			eventBus.dispatch(profilePicChangeEvent);
 			client.send(profilePicChangeEvent);
 			logger.log(Level.INFO, "The user just changed his profile pic.");
@@ -150,14 +178,16 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 		// The username was changed
 		final var validContactName = Bounds.isValidContactName(newUsername);
 		if (usernameChanged && validContactName) {
-			final var nameChangeEvent = new NameChange(userID, newUsername);
+			final var nameChangeEvent = new NameChange(client.getSender().getID(), newUsername);
 			eventBus.dispatch(nameChangeEvent);
 			client.send(nameChangeEvent);
 			logger.log(Level.INFO, "The user just changed his name to " + newUsername + ".");
 		} else if (!validContactName) {
 			final var alert = new Alert(AlertType.ERROR);
 			alert.setTitle("Invalid username");
-			alert.setContentText("The entered username does not conform with the naming limitations: " + Bounds.CONTACT_NAME_PATTERN);
+			alert.setContentText(
+				"The entered username does not conform with the naming limitations: "
+					+ Bounds.CONTACT_NAME_PATTERN);
 			alert.showAndWait();
 			logger.log(Level.INFO, "An invalid username was requested.");
 			return;
@@ -165,7 +195,7 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 
 		// The password was changed
 		if (validPassword) {
-			client.send(new PasswordChangeRequest(newPassword, oldPassword, userID));
+			client.send(new PasswordChangeRequest(newPassword, oldPassword));
 			logger.log(Level.INFO, "The user just tried to change his password!");
 		} else if (!(validPassword || newPassword.isBlank())) {
 			final var alert = new Alert(AlertType.ERROR);

client/src/main/java/envoy/client/ui/settings/package-info.java

@@ -1,6 +1,5 @@
 /**
- * This package contains classes used for representing the settings
- * visually.
+ * This package contains classes used for representing the settings visually.
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart

client/src/main/java/envoy/client/util/IconUtil.java

@@ -9,18 +9,22 @@ import javax.imageio.ImageIO;
 
 import javafx.scene.image.Image;
 
-import envoy.client.data.Settings;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.Settings;
+
 /**
- * Provides static utility methods for loading icons from the resource
- * folder.
+ * Provides static utility methods for loading icons from the resource folder.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
  */
 public final class IconUtil {
 
+	private static final HashMap<String, Image>			cache		= new HashMap<>();
+	private static final HashMap<String, Image>			scaledCache	= new HashMap<>();
+	private static final HashMap<String, BufferedImage>	awtCache	= new HashMap<>();
+
 	private IconUtil() {}
 
 	/**
@@ -30,7 +34,10 @@ public final class IconUtil {
 	 * @return the loaded image
 	 * @since Envoy Client v0.1-beta
 	 */
-	public static Image load(String path) { return new Image(IconUtil.class.getResource(path).toExternalForm()); }
+	public static Image load(String path) {
+		return cache.computeIfAbsent(path,
+			p -> new Image(IconUtil.class.getResource(p).toExternalForm()));
+	}
 
 	/**
 	 * Loads an image from the resource folder and scales it to the given size.
@@ -41,12 +48,14 @@ public final class IconUtil {
 	 * @since Envoy Client v0.1-beta
 	 */
 	public static Image load(String path, int size) {
-		return new Image(IconUtil.class.getResource(path).toExternalForm(), size, size, true, true);
+		return scaledCache.computeIfAbsent(path + size,
+			p -> new Image(IconUtil.class.getResource(path).toExternalForm(), size, size, true,
+				true));
 	}
 
 	/**
-	 * Loads a {@code .png} image from the sub-folder {@code /icons/} of the
-	 * resource folder.<br>
+	 * Loads a {@code .png} image from the sub-folder {@code /icons/} of the resource folder.
+	 * <p>
 	 * The suffix {@code .png} is automatically appended.
 	 *
 	 * @param name the image name without the .png suffix
@@ -55,11 +64,13 @@ public final class IconUtil {
 	 * @apiNote let's load a sample image {@code /icons/abc.png}.<br>
 	 *          To do that, we only have to call {@code IconUtil.loadIcon("abc")}
 	 */
-	public static Image loadIcon(String name) { return load("/icons/" + name + ".png"); }
+	public static Image loadIcon(String name) {
+		return load("/icons/" + name + ".png");
+	}
 
 	/**
-	 * Loads a {@code .png} image from the sub-folder {@code /icons/} of the
-	 * resource folder and scales it to the given size.<br>
+	 * Loads a {@code .png} image from the sub-folder {@code /icons/} of the resource folder and
+	 * scales it to the given size.<br>
 	 * The suffix {@code .png} is automatically appended.
 	 *
 	 * @param name the image name without the .png suffix
@@ -67,20 +78,19 @@ public final class IconUtil {
 	 * @return the loaded image
 	 * @since Envoy Client v0.1-beta
 	 * @apiNote let's load a sample image {@code /icons/abc.png} in size 16.<br>
-	 *          To do that, we only have to call
-	 *          {@code IconUtil.loadIcon("abc", 16)}
+	 *          To do that, we only have to call {@code IconUtil.loadIcon("abc", 16)}
 	 */
-	public static Image loadIcon(String name, int size) { return load("/icons/" + name + ".png", size); }
+	public static Image loadIcon(String name, int size) {
+		return load("/icons/" + name + ".png", size);
+	}
 
 	/**
-	 * Loads a {@code .png} image whose design depends on the currently active theme
-	 * from the sub-folder {@code /icons/dark/} or {@code /icons/light/} of the
-	 * resource folder.
+	 * Loads a {@code .png} image whose design depends on the currently active theme from the
+	 * sub-folder {@code /icons/dark/} or {@code /icons/light/} of the resource folder.
 	 * <p>
 	 * The suffix {@code .png} is automatically appended.
 	 *
-	 * @param name the image name without the "black" or "white" suffix and without
-	 *             the .png suffix
+	 * @param name the image name without the "black" or "white" suffix and without the .png suffix
 	 * @return the loaded image
 	 * @since Envoy Client v0.1-beta
 	 * @apiNote let's take two sample images {@code /icons/dark/abc.png} and
@@ -88,12 +98,14 @@ public final class IconUtil {
 	 *          To do that theme sensitive, we only have to call
 	 *          {@code IconUtil.loadIconThemeSensitive("abc")}
 	 */
-	public static Image loadIconThemeSensitive(String name) { return loadIcon(themeSpecificSubFolder() + name); }
+	public static Image loadIconThemeSensitive(String name) {
+		return loadIcon(themeSpecificSubFolder() + name);
+	}
 
 	/**
-	 * Loads a {@code .png} image whose design depends on the currently active theme
-	 * from the sub-folder {@code /icons/dark/} or {@code /icons/light/} of the
-	 * resource folder and scales it to the given size.
+	 * Loads a {@code .png} image whose design depends on the currently active theme from the
+	 * sub-folder {@code /icons/dark/} or {@code /icons/light/} of the resource folder and scales it
+	 * to the given size.
 	 * <p>
 	 * The suffix {@code .png} is automatically appended.
 	 *
@@ -106,20 +118,19 @@ public final class IconUtil {
 	 *          To do that theme sensitive, we only have to call
 	 *          {@code IconUtil.loadIconThemeSensitive("abc", 16)}
 	 */
-	public static Image loadIconThemeSensitive(String name, int size) { return loadIcon(themeSpecificSubFolder() + name, size); }
+	public static Image loadIconThemeSensitive(String name, int size) {
+		return loadIcon(themeSpecificSubFolder() + name, size);
+	}
 
 	/**
-	 *
-	 * Loads images specified by an enum. The images have to be named like the
-	 * lowercase enum constants with {@code .png} extension and be located inside a
-	 * folder with the lowercase name of the enum, which must be contained inside
-	 * the {@code /icons/} folder.
+	 * Loads images specified by an enum. The images have to be named like the lowercase enum
+	 * constants with {@code .png} extension and be located inside a folder with the lowercase name
+	 * of the enum, which must be contained inside the {@code /icons/} folder.
 	 *
 	 * @param <T>       the enum that specifies the images to load
 	 * @param enumClass the class of the enum
 	 * @param size      the size to scale the images to
-	 * @return a map containing the loaded images with the corresponding enum
-	 *         constants as keys
+	 * @return a map containing the loaded images with the corresponding enum constants as keys
 	 * @since Envoy Client v0.1-beta
 	 */
 	public static <T extends Enum<T>> EnumMap<T, Image> loadByEnum(Class<T> enumClass, int size) {
@@ -138,25 +149,29 @@ public final class IconUtil {
 	 * @since Envoy Client v0.2-beta
 	 */
 	public static BufferedImage loadAWTCompatible(String path) {
-		BufferedImage image = null;
+		return awtCache.computeIfAbsent(path, p -> {
 			try {
-			image = ImageIO.read(IconUtil.class.getResource(path));
-		} catch (final IOException e) {
-			EnvoyLog.getLogger(IconUtil.class).log(Level.WARNING, String.format("Could not load image at path %s: ", path), e);
+				return ImageIO.read(IconUtil.class.getResource(path));
+			} catch (IOException e) {
+				EnvoyLog.getLogger(IconUtil.class).log(Level.WARNING,
+					String.format("Could not load image at path %s: ", path), e);
+				return null;
 			}
-		return image;
+		});
 	}
 
 	/**
-	 * This method should be called if the display of an image depends upon the
-	 * currently active theme.<br>
-	 * In case of a default theme, the string returned will be
-	 * ({@code dark/} or {@code light/}), otherwise it will be empty.
+	 * This method should be called if the display of an image depends upon the currently active
+	 * theme.<br>
+	 * In case of a default theme, the string returned will be ({@code dark/} or {@code light/}),
+	 * otherwise it will be empty.
 	 *
 	 * @return the theme specific folder
 	 * @since Envoy Client v0.1-beta
 	 */
 	private static String themeSpecificSubFolder() {
-		return Settings.getInstance().isUsingDefaultTheme() ? Settings.getInstance().getCurrentTheme() + "/" : "";
+		return Settings.getInstance().isUsingDefaultTheme()
+			? Settings.getInstance().getCurrentTheme() + "/"
+			: "";
 	}
 }

client/src/main/java/envoy/client/util/MessageUtil.java

@@ -0,0 +1,116 @@
+package envoy.client.util;
+
+import java.awt.Toolkit;
+import java.awt.datatransfer.StringSelection;
+import java.io.*;
+import java.util.logging.*;
+
+import javafx.stage.FileChooser;
+
+import dev.kske.eventbus.core.EventBus;
+
+import envoy.data.Message;
+import envoy.util.EnvoyLog;
+
+import envoy.client.data.*;
+import envoy.client.event.MessageDeletion;
+import envoy.client.ui.controller.ChatScene;
+
+/**
+ * Contains methods that are commonly used for {@link Message}s.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public class MessageUtil {
+
+	private MessageUtil() {}
+
+	private static Logger logger = EnvoyLog.getLogger(MessageUtil.class);
+
+	/**
+	 * Copies the text of the given message to the System Clipboard.
+	 *
+	 * @param message the message whose text to copy
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void copyMessageText(Message message) {
+		logger.log(Level.FINEST,
+			"A copy of message text \"" + message.getText() + "\" was requested");
+		Toolkit.getDefaultToolkit().getSystemClipboard()
+			.setContents(new StringSelection(message.getText()), null);
+	}
+
+	/**
+	 * Deletes the given message.
+	 *
+	 * @param message the message to delete
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void deleteMessage(Message message) {
+		final var	messageDeletionEvent	= new MessageDeletion(message.getID());
+		final var	controller				=
+			Context.getInstance().getSceneContext().getController();
+		if (controller instanceof ChatScene)
+			((ChatScene) controller).clearMessageSelection();
+
+		// Removing the message locally
+		EventBus.getInstance().dispatch(messageDeletionEvent);
+
+		logger.log(Level.FINEST, "message deletion was requested for " + message);
+	}
+
+	/**
+	 * Forwards the given message. Currently not implemented.
+	 *
+	 * @param message the message to forward
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void forwardMessage(Message message) {
+		logger.log(Level.FINEST, "Message forwarding was requested for " + message);
+	}
+
+	/**
+	 * Quotes the given message. Currently not implemented.
+	 *
+	 * @param message the message to quote
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void quoteMessage(Message message) {
+		logger.log(Level.FINEST, "Message quotation was requested for " + message);
+	}
+
+	/**
+	 * Saves the attachment of a message, if present.
+	 *
+	 * @param message the message whose attachment to save
+	 * @throws IllegalStateException if no attachment is present in the message
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void saveAttachment(Message message) {
+		if (!message.hasAttachment())
+			throw new IllegalArgumentException("Cannot save a non-existing attachment");
+		File		file;
+		final var	fileName			= message.getAttachment().getName();
+		final var	downloadLocation	= Settings.getInstance().getDownloadLocation();
+
+		// Show save file dialog, if the user did not opt-out
+		if (!Settings.getInstance().isDownloadSavedWithoutAsking()) {
+			final var fileChooser = new FileChooser();
+			fileChooser.setInitialFileName(fileName);
+			fileChooser.setInitialDirectory(downloadLocation);
+			file = fileChooser.showSaveDialog(Context.getInstance().getSceneContext().getStage());
+		} else
+			file = new File(downloadLocation, fileName);
+
+		// A file was selected
+		if (file != null)
+			try (var fos = new FileOutputStream(file)) {
+				fos.write(message.getAttachment().getData());
+				logger.log(Level.FINE,
+					"Attachment of message was saved at " + file.getAbsolutePath());
+			} catch (final IOException e) {
+				logger.log(Level.WARNING, "Could not save attachment of " + message + ": ", e);
+			}
+	}
+}

client/src/main/java/envoy/client/util/ReflectionUtil.java

@@ -14,26 +14,25 @@ public final class ReflectionUtil {
 	private ReflectionUtil() {}
 
 	/**
-	 * Gets all declared variable values of the given instance that have the
-	 * specified class.
+	 * Gets all declared variable values of the given instance that have the specified class.
 	 * <p>
-	 * (i.e. can get all {@code JComponents} (Swing) or {@code Nodes} (JavaFX) in a
-	 * GUI class).
+	 * (i.e. can get all {@code JComponents} (Swing) or {@code Nodes} (JavaFX) in a GUI class).
 	 * <p>
 	 * <b>Important: If you are using a module, you first need to declare <br>
 	 * "opens {your_package} to envoy.client.util;" in your module-info.java</b>.
 	 *
 	 * @param <T>          the type of the object
 	 * @param <R>          the type to return
-	 * @param instance     the instance of a given class whose values are to be
-	 *                     evaluated
+	 * @param instance     the instance of a given class whose values are to be evaluated
 	 * @param typeToReturn the type of variable to return
 	 * @return all variables in the given instance that have the requested type
 	 * @throws RuntimeException if an exception occurs
 	 * @since Envoy Client v0.2-beta
 	 */
-	public static <T, R> Stream<R> getAllDeclaredVariablesOfTypeAsStream(T instance, Class<R> typeToReturn) {
-		return Arrays.stream(instance.getClass().getDeclaredFields()).filter(field -> typeToReturn.isAssignableFrom(field.getType())).map(field -> {
+	public static <T, R> Stream<R> getAllDeclaredVariablesOfTypeAsStream(T instance,
+		Class<R> typeToReturn) {
+		return Arrays.stream(instance.getClass().getDeclaredFields())
+			.filter(field -> typeToReturn.isAssignableFrom(field.getType())).map(field -> {
 				try {
 					field.setAccessible(true);
 					return typeToReturn.cast(field.get(instance));
@@ -44,17 +43,14 @@ public final class ReflectionUtil {
 	}
 
 	/**
-	 * Gets all declared variables of the given instance that are children of
-	 * {@code Node}.
+	 * Gets all declared variables of the given instance that are children of {@code Node}.
 	 * <p>
 	 * <b>Important: If you are using a module, you first need to declare <br>
 	 * "opens {your_package} to envoy.client.util;" in your module-info.java</b>.
 	 *
 	 * @param <T>      the type of the instance
-	 * @param instance the instance of a given class whose values are to be
-	 *                 evaluated
-	 * @return all variables of the given object that have the requested type as
-	 *         {@code Stream}
+	 * @param instance the instance of a given class whose values are to be evaluated
+	 * @return all variables of the given object that have the requested type as {@code Stream}
 	 * @since Envoy Client v0.2-beta
 	 */
 	public static <T> Stream<Node> getAllDeclaredNodeVariablesAsStream(T instance) {
@@ -62,15 +58,13 @@ public final class ReflectionUtil {
 	}
 
 	/**
-	 * Gets all declared variables of the given instance that are children of
-	 * {@code Node}<br>
+	 * Gets all declared variables of the given instance that are children of {@code Node}<br>
 	 * <p>
 	 * <b>Important: If you are using a module, you first need to declare <br>
 	 * "opens {your_package} to envoy.client.util;" in your module-info.java</b>.
 	 *
 	 * @param <T>      the type of the instance
-	 * @param instance the instance of a given class whose values are to be
-	 *                 evaluated
+	 * @param instance the instance of a given class whose values are to be evaluated
 	 * @return all variables of the given object that have the requested type
 	 * @since Envoy Client v0.2-beta
 	 */

client/src/main/java/envoy/client/util/UserUtil.java

@@ -0,0 +1,155 @@
+package envoy.client.util;
+
+import java.util.logging.*;
+
+import javafx.scene.control.*;
+import javafx.scene.control.Alert.AlertType;
+
+import dev.kske.eventbus.core.EventBus;
+
+import envoy.data.*;
+import envoy.data.User.UserStatus;
+import envoy.event.*;
+import envoy.event.contact.UserOperation;
+import envoy.util.EnvoyLog;
+
+import envoy.client.data.Context;
+import envoy.client.event.*;
+import envoy.client.helper.*;
+import envoy.client.ui.SceneInfo;
+import envoy.client.ui.controller.ChatScene;
+
+/**
+ * Contains methods that change something about the currently logged in user.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public final class UserUtil {
+
+	private static final Context	context	= Context.getInstance();
+	private static final Logger		logger	= EnvoyLog.getLogger(UserUtil.class);
+
+	private UserUtil() {}
+
+	/**
+	 * Logs the current user out and reopens {@link envoy.client.ui.controller.LoginScene}.
+	 *
+	 * @since Envoy Client v0.2-beta
+	 */
+	public static void logout() {
+		final var alert = new Alert(AlertType.CONFIRMATION);
+		alert.setTitle("Logout?");
+		alert.setContentText("Are you sure you want to log out?");
+
+		AlertHelper.confirmAction(alert, () -> {
+			EnvoyLog.getLogger(ShutdownHelper.class).log(Level.INFO, "A logout was requested");
+			EventBus.getInstance().dispatch(new EnvoyCloseEvent());
+			EventBus.getInstance().dispatch(new Logout());
+			context.getSceneContext().load(SceneInfo.LOGIN_SCENE);
+			logger.log(Level.INFO, "A logout occurred.");
+		});
+	}
+
+	/**
+	 * Notifies the application that the status of the currently logged in user has changed.
+	 *
+	 * @param newStatus the new status
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void changeStatus(UserStatus newStatus) {
+
+		// Sending the already active status is a valid action
+		if (newStatus.equals(context.getLocalDB().getUser().getStatus()))
+			return;
+		else {
+			EventBus.getInstance().dispatch(new OwnStatusChange(newStatus));
+			if (context.getClient().isOnline())
+				context.getClient()
+					.send(new UserStatusChange(context.getLocalDB().getUser().getID(), newStatus));
+			logger.log(Level.INFO, "A manual status change occurred.");
+		}
+	}
+
+	/**
+	 * Removes the given contact.
+	 *
+	 * @param block the contact that should be removed
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void disableContact(Contact block) {
+		if (!context.getClient().isOnline() || block == null)
+			return;
+		else {
+			final var alert = new Alert(AlertType.CONFIRMATION);
+			alert.setContentText("Are you sure you want to "
+				+ (block instanceof User ? "block " : "leave group ") + block.getName() + "?");
+			AlertHelper.confirmAction(alert, () -> {
+				final var isUser = block instanceof User;
+				context.getClient()
+					.send(isUser ? new UserOperation((User) block, ElementOperation.REMOVE)
+						: new GroupResize(context.getLocalDB().getUser(), (Group) block,
+							ElementOperation.REMOVE));
+				if (!isUser)
+					block.getContacts().remove(context.getLocalDB().getUser());
+				EventBus.getInstance().dispatch(new ContactDisabled(block));
+				logger.log(Level.INFO, isUser ? "A user was blocked." : "The user left a group.");
+			});
+		}
+	}
+
+	/**
+	 * Deletes the given contact with all his messages entirely.
+	 *
+	 * @param delete the contact to delete
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void deleteContact(Contact delete) {
+		if (delete == null)
+			return;
+		else {
+			final var alert = new Alert(AlertType.CONFIRMATION);
+			alert.setContentText("Are you sure you want to delete " + delete.getName()
+				+ " entirely? All messages with this contact will be deleted. This action cannot be undone.");
+			AlertHelper.confirmAction(alert, () -> {
+				context.getLocalDB().getUsers().remove(delete.getName());
+				context.getLocalDB().getChats()
+					.removeIf(chat -> chat.getRecipient().equals(delete));
+				if (context.getSceneContext().getController() instanceof ChatScene)
+					((ChatScene) context.getSceneContext().getController()).resetState();
+				logger.log(Level.INFO, "A contact with all his messages was deleted.");
+			});
+		}
+	}
+
+	/**
+	 * Deletes anything pointing to this user, independent of client or server. Will do nothing if
+	 * the client is currently offline.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void deleteAccount() {
+
+		// Show the first wall of defense, if not disabled by the user
+		final var outerAlert = new Alert(AlertType.CONFIRMATION);
+		outerAlert.setContentText(
+			"Are you sure you want to delete your account entirely? This action can seriously not be undone.");
+		outerAlert.setTitle("Delete Account?");
+		AlertHelper.confirmAction(outerAlert, () -> {
+
+			// Show the final wall of defense in every case
+			final var lastAlert = new Alert(AlertType.WARNING,
+				"Do you REALLY want to delete your account? Last Warning. Proceed?",
+				ButtonType.CANCEL, ButtonType.OK);
+			lastAlert.setTitle("Delete Account?");
+			lastAlert.showAndWait().filter(ButtonType.OK::equals).ifPresent(b2 -> {
+
+				// Delete the account
+				// TODO: Notify server of account deletion
+				context.getLocalDB().delete();
+				logger.log(Level.INFO, "The user just deleted his account. Goodbye.");
+				ShutdownHelper.exit(true);
+			});
+		});
+	}
+}

client/src/main/java/module-info.java

@@ -1,6 +1,5 @@
 /**
- * This module contains all classes defining the client application of the Envoy
- * project.
+ * This module contains all classes defining the client application of the Envoy project.
  *
  * @author Kai S. K. Engelbart
  * @author Leon Hofmeister
@@ -17,11 +16,13 @@ module envoy.client {
 	requires javafx.fxml;
 	requires javafx.base;
 	requires javafx.graphics;
+	requires dev.kske.eventbus.core;
 
-	opens envoy.client.ui to javafx.graphics, javafx.fxml, dev.kske.eventbus;
-	opens envoy.client.ui.controller to javafx.graphics, javafx.fxml, envoy.client.util, dev.kske.eventbus;
+	opens envoy.client.ui to javafx.graphics, javafx.fxml, dev.kske.eventbus.core;
+	opens envoy.client.ui.controller to javafx.graphics, javafx.fxml, envoy.client.util, dev.kske.eventbus.core;
+	opens envoy.client.ui.chatscene to javafx.graphics, javafx.fxml, envoy.client.util, dev.kske.eventbus.core;
 	opens envoy.client.ui.control to javafx.graphics, javafx.fxml;
 	opens envoy.client.ui.settings to envoy.client.util;
-	opens envoy.client.net to dev.kske.eventbus;
-	opens envoy.client.data to dev.kske.eventbus;
+	opens envoy.client.net to dev.kske.eventbus.core;
+	opens envoy.client.data to dev.kske.eventbus.core;
 }

client/src/main/resources/client.properties

@@ -1,6 +1,5 @@
+fileLevelBarrier=OFF
+consoleLevelBarrier=FINER
 server=localhost
 port=8080
-localDB=localDB
 localDBSaveInterval=2
-consoleLevelBarrier=FINER
-fileLevelBarrier=OFF

client/src/main/resources/css/base.css

@@ -4,8 +4,10 @@
 
 .context-menu, .context-menu > * {
 	-fx-background-radius: 15.0px;
-	/*TODO: solution below does not work */
-	-fx-background-color: transparent;
+}
+
+.list-cell:selected, .menu-item:hover, .combo-box-popup .list-view .list-cell:selected {
+    -fx-background-color: #454c4f;
 }
 
 #text-enter-container, #contact-search-enter-container {
@@ -39,7 +41,7 @@
 	-fx-scale-y: 1.05;
 }
 
-.label {
+.label, .quick-select {
 	-fx-background-color: transparent;
 }
 
@@ -68,6 +70,17 @@
 	-fx-text-fill: gray;
 }
 
+.danger-button {
+	-fx-background-color: red;
+	-fx-text-fill: white;
+	-fx-background-radius: 0.2em;
+}
+
+.danger-button:hover {
+	-fx-scale-x: 1.05;
+	-fx-scale-y: 1.05;
+}
+
 .received-message {
 	-fx-alignment: center-left;
 	-fx-background-radius: 1.3em;
@@ -138,7 +151,24 @@
 .tab-pane {
     -fx-tab-max-height: 0.0 ;
 }
+
 .tab-pane .tab-header-area {
     visibility: hidden ;
     -fx-padding: -20.0 0.0 0.0 0.0;
 }
+
+.disabled-chat {
+	-fx-background-color: #0000FF;
+}
+
+#quick-select-list .scroll-bar:horizontal{
+	-fx-pref-height: 0.0;
+	-fx-max-height: 0.0;
+	-fx-min-height: 0.0; 
+}
+
+#quick-select-list .scroll-bar:vertical{
+	-fx-pref-width: 0.0;
+	-fx-max-width: 0.0;
+	-fx-min-width: 0.0; 
+}

client/src/main/resources/css/dark.css

@@ -18,14 +18,10 @@
 	-fx-background-color: lightgray;
 }
 
-#message-list, .text-field, .password-field, .tooltip, .pane, .pane .content, .vbox, .titled-pane > .title, .titled-pane > *.content, .context-menu, .menu-item {
+#message-list, .text-field, .password-field, .tooltip, .pane, .pane .content, .vbox, .titled-pane > .title, .titled-pane > *.content, .context-menu, .menu-item, .combo-box-popup .list-view .list-cell, #quick-select-list {
 	-fx-background-color: #222222;
 }
 
-.list-cell:selected, .list-cell:selected > *, .menu-item:hover {
-    -fx-background-color: #690099;
-}
-
 .received-message {
 	-fx-background-color: gray;
 }
@@ -73,7 +69,7 @@
 	-fx-background-color: transparent;
 }
 
-.scroll-bar:vertical .increment-arrow, .scroll-bar:vertical .decrement-arrow {
+.scroll-bar:vertical .increment-arrow, .scroll-bar:vertical .decrement-arrow, .list-cell {
 	-fx-background-color: transparent;
 }
 
@@ -87,3 +83,8 @@
 	-fx-text-fill: white;
 	-fx-background-color: transparent;
 }
+
+#remove-button {
+	-fx-background-color: red;
+	-fx-background-radius: 1em;
+}

client/src/main/resources/css/light.css

@@ -18,10 +18,6 @@
 	-fx-background-color: #E3E3E3;
 }
 
-.list-cell:selected, .list-cell:selected > *, .menu-item:hover {
-    -fx-background-color: #805959;
-}
-
 .received-message {
 	-fx-background-color: lightgray;
 }
@@ -34,6 +30,10 @@
 	-fx-background-color: black;
 }
 
+.tooltip {
+	-fx-text-fill: black;
+}
+
 #login-input-field {
 	-fx-border-color: black;
 }

client/src/main/resources/fxml/ChatScene.fxml

@@ -20,13 +20,18 @@
 <?import javafx.scene.layout.RowConstraints?>
 <?import javafx.scene.layout.VBox?>
 <?import javafx.scene.text.Font?>
+<?import javafx.stage.Screen?>
 
-<GridPane fx:id="scene" maxHeight="-Infinity"
-	maxWidth="-Infinity" minHeight="400.0" minWidth="500.0"
-	prefHeight="1152.0" prefWidth="2042.0"
+<GridPane maxHeight="-Infinity" maxWidth="-Infinity"
+	minHeight="400.0" minWidth="500.0"
+	prefWidth="${screen.visualBounds.width}"
+	prefHeight="${screen.visualBounds.height}"
 	xmlns="http://javafx.com/javafx/11.0.1"
 	xmlns:fx="http://javafx.com/fxml/1"
 	fx:controller="envoy.client.ui.controller.ChatScene">
+	<fx:define>
+		<Screen fx:factory="getPrimary" fx:id="screen" />
+	</fx:define>
 	<columnConstraints>
 		<ColumnConstraints hgrow="NEVER"
 			maxWidth="327.99997965494794" minWidth="-Infinity" prefWidth="317.0" />
@@ -52,8 +57,7 @@
 					<content>
 						<AnchorPane minHeight="0.0" minWidth="0.0">
 							<children>
-								<VBox fx:id="contactOperations" prefHeight="3000.0"
-									prefWidth="316.0">
+								<VBox prefHeight="3000.0" prefWidth="316.0">
 									<children>
 										<VBox id="search-panel" maxHeight="-Infinity"
 											minHeight="-Infinity" prefHeight="80.0" prefWidth="316.0">
@@ -121,15 +125,6 @@
 										<ListView id="chat-list" fx:id="chatList"
 											focusTraversable="false" onMouseClicked="#chatListClicked"
 											prefWidth="316.0" VBox.vgrow="ALWAYS">
-											<contextMenu>
-												<ContextMenu anchorLocation="CONTENT_TOP_LEFT">
-													<items>
-														<MenuItem fx:id="deleteContactMenuItem"
-															mnemonicParsing="false" onAction="#deleteContact"
-															text="Delete" />
-													</items>
-												</ContextMenu>
-											</contextMenu>
 											<padding>
 												<Insets bottom="5.0" left="5.0" right="2.0" top="5.0" />
 											</padding>
@@ -150,50 +145,27 @@
 				<Insets right="1.0" />
 			</GridPane.margin>
 		</TabPane>
-		<HBox id="top-bar" alignment="CENTER_LEFT" prefHeight="100.0">
+		<HBox id="top-bar" alignment="CENTER_LEFT" prefHeight="100.0"
+			fx:id="ownContactControl">
 			<children>
 				<ImageView id="profile-pic" fx:id="clientProfilePic"
 					fitHeight="43.0" fitWidth="43.0" pickOnBounds="true"
 					preserveRatio="true">
 					<HBox.margin>
-						<Insets left="15.0" top="5.0" />
+						<Insets left="15.0" top="5.0" right="10.0" />
 					</HBox.margin>
 				</ImageView>
-				<Label id="transparent-background" fx:id="contactLabel"
-					prefHeight="27.0" prefWidth="134.0">
-					<padding>
-						<Insets bottom="5.0" left="5.0" right="5.0" top="5.0" />
-					</padding>
-					<font>
-						<Font size="18.0" />
-					</font>
-					<HBox.margin>
-						<Insets left="10.0" top="5.0" />
-					</HBox.margin>
-				</Label>
-				<Region id="transparent-background" prefHeight="77.0"
-					prefWidth="115.0" />
-				<VBox id="transparent-background" alignment="CENTER_RIGHT"
-					prefHeight="200.0" prefWidth="100.0" spacing="5.0">
-					<children>
-						<Button fx:id="settingsButton" mnemonicParsing="true"
+				<Region id="transparent-background" HBox.hgrow="ALWAYS" />
+				<Button fx:id="settingsButton" mnemonicParsing="false"
 					onAction="#settingsButtonClicked" prefHeight="30.0"
-							prefWidth="30.0" text="">
+					prefWidth="30.0" alignment="CENTER_RIGHT">
 					<padding>
 						<Insets bottom="5.0" left="5.0" right="5.0" top="5.0" />
 					</padding>
-							<VBox.margin>
-								<Insets />
-							</VBox.margin>
-						</Button>
-					</children>
 					<HBox.margin>
-						<Insets right="10.0" />
+						<Insets bottom="35.0" left="5.0" top="35.0" right="10.0" />
 					</HBox.margin>
-					<opaqueInsets>
-						<Insets />
-					</opaqueInsets>
-				</VBox>
+				</Button>
 			</children>
 			<GridPane.margin>
 				<Insets bottom="1.0" right="1.0" />

client/src/main/resources/fxml/GroupCreationTab.fxml

@@ -64,6 +64,7 @@
                <Insets bottom="5.0" top="5" />
             </VBox.margin>
          </Label>
+         <ListView fx:id="quickSelectList" id="quick-select-list" orientation="HORIZONTAL" prefHeight="60.0" />
          <ListView id="chat-list" fx:id="userList" focusTraversable="false" onMouseClicked="#userListClicked" prefWidth="316.0" VBox.vgrow="ALWAYS">
             <contextMenu>
                <ContextMenu anchorLocation="CONTENT_TOP_LEFT" />

client/src/main/resources/fxml/SettingsScene.fxml

@@ -7,11 +7,16 @@
 <?import javafx.scene.layout.HBox?>
 <?import javafx.scene.layout.VBox?>
 
-<VBox alignment="TOP_RIGHT" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="envoy.client.ui.controller.SettingsScene">
+<VBox alignment="TOP_RIGHT" maxHeight="-Infinity" minHeight="400.0"
+	minWidth="500.0" xmlns="http://javafx.com/javafx/11.0.1"
+	xmlns:fx="http://javafx.com/fxml/1"
+	fx:controller="envoy.client.ui.controller.SettingsScene">
 	<children>
 		<HBox prefHeight="389.0" prefWidth="600.0">
 			<children>
-				<ListView id="message-list" fx:id="settingsList" onMouseClicked="#settingsListClicked" prefHeight="200.0" prefWidth="200.0">
+				<ListView id="message-list" fx:id="settingsList"
+					onMouseClicked="#settingsListClicked" prefHeight="200.0"
+					prefWidth="200.0">
 					<opaqueInsets>
 						<Insets bottom="5.0" left="5.0" right="5.0" top="5.0" />
 					</opaqueInsets>
@@ -22,7 +27,8 @@
 						<Insets bottom="5.0" left="5.0" right="5.0" top="5.0" />
 					</padding>
 				</ListView>
-				<TitledPane fx:id="titledPane" collapsible="false" prefHeight="400.0" prefWidth="400.0">
+				<TitledPane fx:id="titledPane" collapsible="false"
+					prefHeight="400.0" prefWidth="400.0">
 					<HBox.margin>
 						<Insets bottom="10.0" left="5.0" right="10.0" top="10.0" />
 					</HBox.margin>
@@ -32,7 +38,8 @@
 				</TitledPane>
 			</children>
 		</HBox>
-		<Button defaultButton="true" mnemonicParsing="true" onMouseClicked="#backButtonClicked" text="_Back">
+		<Button defaultButton="true" mnemonicParsing="true"
+			onMouseClicked="#backButtonClicked" text="_Back">
 			<opaqueInsets>
 				<Insets />
 			</opaqueInsets>

common/.settings/org.eclipse.jdt.core.prefs

@@ -128,364 +128,4 @@ org.eclipse.jdt.core.compiler.problem.unusedWarningToken=warning
 org.eclipse.jdt.core.compiler.problem.varargsArgumentNeedCast=warning
 org.eclipse.jdt.core.compiler.release=disabled
 org.eclipse.jdt.core.compiler.source=11
-org.eclipse.jdt.core.formatter.align_assignment_statements_on_columns=true
-org.eclipse.jdt.core.formatter.align_fields_grouping_blank_lines=1
-org.eclipse.jdt.core.formatter.align_type_members_on_columns=true
-org.eclipse.jdt.core.formatter.align_variable_declarations_on_columns=true
-org.eclipse.jdt.core.formatter.align_with_spaces=false
-org.eclipse.jdt.core.formatter.alignment_for_additive_operator=16
-org.eclipse.jdt.core.formatter.alignment_for_arguments_in_allocation_expression=16
-org.eclipse.jdt.core.formatter.alignment_for_arguments_in_annotation=84
-org.eclipse.jdt.core.formatter.alignment_for_arguments_in_enum_constant=16
-org.eclipse.jdt.core.formatter.alignment_for_arguments_in_explicit_constructor_call=16
-org.eclipse.jdt.core.formatter.alignment_for_arguments_in_method_invocation=80
-org.eclipse.jdt.core.formatter.alignment_for_arguments_in_qualified_allocation_expression=20
-org.eclipse.jdt.core.formatter.alignment_for_assignment=0
-org.eclipse.jdt.core.formatter.alignment_for_bitwise_operator=16
-org.eclipse.jdt.core.formatter.alignment_for_compact_if=16
-org.eclipse.jdt.core.formatter.alignment_for_compact_loops=16
-org.eclipse.jdt.core.formatter.alignment_for_conditional_expression=80
-org.eclipse.jdt.core.formatter.alignment_for_conditional_expression_chain=0
-org.eclipse.jdt.core.formatter.alignment_for_enum_constants=16
-org.eclipse.jdt.core.formatter.alignment_for_expressions_in_array_initializer=16
-org.eclipse.jdt.core.formatter.alignment_for_expressions_in_for_loop_header=0
-org.eclipse.jdt.core.formatter.alignment_for_logical_operator=16
-org.eclipse.jdt.core.formatter.alignment_for_method_declaration=0
-org.eclipse.jdt.core.formatter.alignment_for_module_statements=16
-org.eclipse.jdt.core.formatter.alignment_for_multiple_fields=16
-org.eclipse.jdt.core.formatter.alignment_for_multiplicative_operator=16
-org.eclipse.jdt.core.formatter.alignment_for_parameterized_type_references=0
-org.eclipse.jdt.core.formatter.alignment_for_parameters_in_constructor_declaration=16
-org.eclipse.jdt.core.formatter.alignment_for_parameters_in_method_declaration=16
-org.eclipse.jdt.core.formatter.alignment_for_relational_operator=0
-org.eclipse.jdt.core.formatter.alignment_for_resources_in_try=80
-org.eclipse.jdt.core.formatter.alignment_for_selector_in_method_invocation=84
-org.eclipse.jdt.core.formatter.alignment_for_shift_operator=0
-org.eclipse.jdt.core.formatter.alignment_for_string_concatenation=16
-org.eclipse.jdt.core.formatter.alignment_for_superclass_in_type_declaration=16
-org.eclipse.jdt.core.formatter.alignment_for_superinterfaces_in_enum_declaration=16
-org.eclipse.jdt.core.formatter.alignment_for_superinterfaces_in_type_declaration=16
-org.eclipse.jdt.core.formatter.alignment_for_throws_clause_in_constructor_declaration=16
-org.eclipse.jdt.core.formatter.alignment_for_throws_clause_in_method_declaration=16
-org.eclipse.jdt.core.formatter.alignment_for_type_arguments=0
-org.eclipse.jdt.core.formatter.alignment_for_type_parameters=0
-org.eclipse.jdt.core.formatter.alignment_for_union_type_in_multicatch=16
-org.eclipse.jdt.core.formatter.blank_lines_after_imports=1
-org.eclipse.jdt.core.formatter.blank_lines_after_last_class_body_declaration=0
-org.eclipse.jdt.core.formatter.blank_lines_after_package=1
-org.eclipse.jdt.core.formatter.blank_lines_before_abstract_method=1
-org.eclipse.jdt.core.formatter.blank_lines_before_field=0
-org.eclipse.jdt.core.formatter.blank_lines_before_first_class_body_declaration=1
-org.eclipse.jdt.core.formatter.blank_lines_before_imports=1
-org.eclipse.jdt.core.formatter.blank_lines_before_member_type=1
-org.eclipse.jdt.core.formatter.blank_lines_before_method=1
-org.eclipse.jdt.core.formatter.blank_lines_before_new_chunk=1
-org.eclipse.jdt.core.formatter.blank_lines_before_package=0
-org.eclipse.jdt.core.formatter.blank_lines_between_import_groups=1
-org.eclipse.jdt.core.formatter.blank_lines_between_statement_group_in_switch=0
-org.eclipse.jdt.core.formatter.blank_lines_between_type_declarations=1
-org.eclipse.jdt.core.formatter.brace_position_for_annotation_type_declaration=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_anonymous_type_declaration=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_array_initializer=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_block=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_block_in_case=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_constructor_declaration=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_enum_constant=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_enum_declaration=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_lambda_body=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_method_declaration=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_switch=end_of_line
-org.eclipse.jdt.core.formatter.brace_position_for_type_declaration=end_of_line
-org.eclipse.jdt.core.formatter.comment.align_tags_descriptions_grouped=true
-org.eclipse.jdt.core.formatter.comment.align_tags_names_descriptions=false
-org.eclipse.jdt.core.formatter.comment.clear_blank_lines_in_block_comment=true
-org.eclipse.jdt.core.formatter.comment.clear_blank_lines_in_javadoc_comment=false
-org.eclipse.jdt.core.formatter.comment.count_line_length_from_starting_position=true
-org.eclipse.jdt.core.formatter.comment.format_block_comments=true
-org.eclipse.jdt.core.formatter.comment.format_header=true
-org.eclipse.jdt.core.formatter.comment.format_html=true
-org.eclipse.jdt.core.formatter.comment.format_javadoc_comments=true
-org.eclipse.jdt.core.formatter.comment.format_line_comments=true
-org.eclipse.jdt.core.formatter.comment.format_source_code=true
-org.eclipse.jdt.core.formatter.comment.indent_parameter_description=false
-org.eclipse.jdt.core.formatter.comment.indent_root_tags=false
-org.eclipse.jdt.core.formatter.comment.indent_tag_description=false
-org.eclipse.jdt.core.formatter.comment.insert_new_line_before_root_tags=insert
-org.eclipse.jdt.core.formatter.comment.insert_new_line_between_different_tags=do not insert
-org.eclipse.jdt.core.formatter.comment.insert_new_line_for_parameter=do not insert
-org.eclipse.jdt.core.formatter.comment.line_length=80
-org.eclipse.jdt.core.formatter.comment.new_lines_at_block_boundaries=true
-org.eclipse.jdt.core.formatter.comment.new_lines_at_javadoc_boundaries=true
-org.eclipse.jdt.core.formatter.comment.preserve_white_space_between_code_and_line_comments=false
-org.eclipse.jdt.core.formatter.compact_else_if=true
-org.eclipse.jdt.core.formatter.continuation_indentation=2
-org.eclipse.jdt.core.formatter.continuation_indentation_for_array_initializer=2
-org.eclipse.jdt.core.formatter.disabling_tag=@formatter\:off
-org.eclipse.jdt.core.formatter.enabling_tag=@formatter\:on
-org.eclipse.jdt.core.formatter.format_guardian_clause_on_one_line=true
-org.eclipse.jdt.core.formatter.format_line_comment_starting_on_first_column=true
-org.eclipse.jdt.core.formatter.indent_body_declarations_compare_to_annotation_declaration_header=true
-org.eclipse.jdt.core.formatter.indent_body_declarations_compare_to_enum_constant_header=true
-org.eclipse.jdt.core.formatter.indent_body_declarations_compare_to_enum_declaration_header=true
-org.eclipse.jdt.core.formatter.indent_body_declarations_compare_to_type_header=true
-org.eclipse.jdt.core.formatter.indent_breaks_compare_to_cases=true
-org.eclipse.jdt.core.formatter.indent_empty_lines=false
-org.eclipse.jdt.core.formatter.indent_statements_compare_to_block=true
-org.eclipse.jdt.core.formatter.indent_statements_compare_to_body=true
-org.eclipse.jdt.core.formatter.indent_switchstatements_compare_to_cases=true
-org.eclipse.jdt.core.formatter.indent_switchstatements_compare_to_switch=true
-org.eclipse.jdt.core.formatter.indentation.size=4
-org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_enum_constant=insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_field=insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_local_variable=insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_method=insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_package=insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_parameter=do not insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_annotation_on_type=insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_label=insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_opening_brace_in_array_initializer=do not insert
-org.eclipse.jdt.core.formatter.insert_new_line_after_type_annotation=do not insert
-org.eclipse.jdt.core.formatter.insert_new_line_at_end_of_file_if_missing=insert
-org.eclipse.jdt.core.formatter.insert_new_line_before_catch_in_try_statement=do not insert
-org.eclipse.jdt.core.formatter.insert_new_line_before_closing_brace_in_array_initializer=do not insert
-org.eclipse.jdt.core.formatter.insert_new_line_before_else_in_if_statement=do not insert
-org.eclipse.jdt.core.formatter.insert_new_line_before_finally_in_try_statement=do not insert
-org.eclipse.jdt.core.formatter.insert_new_line_before_while_in_do_statement=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_additive_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_after_and_in_type_parameter=insert
-org.eclipse.jdt.core.formatter.insert_space_after_arrow_in_switch_case=insert
-org.eclipse.jdt.core.formatter.insert_space_after_arrow_in_switch_default=insert
-org.eclipse.jdt.core.formatter.insert_space_after_assignment_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_after_at_in_annotation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_at_in_annotation_type_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_bitwise_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_after_closing_angle_bracket_in_type_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_closing_angle_bracket_in_type_parameters=insert
-org.eclipse.jdt.core.formatter.insert_space_after_closing_brace_in_block=insert
-org.eclipse.jdt.core.formatter.insert_space_after_closing_paren_in_cast=insert
-org.eclipse.jdt.core.formatter.insert_space_after_colon_in_assert=insert
-org.eclipse.jdt.core.formatter.insert_space_after_colon_in_case=insert
-org.eclipse.jdt.core.formatter.insert_space_after_colon_in_conditional=insert
-org.eclipse.jdt.core.formatter.insert_space_after_colon_in_for=insert
-org.eclipse.jdt.core.formatter.insert_space_after_colon_in_labeled_statement=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_allocation_expression=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_annotation=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_array_initializer=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_constructor_declaration_parameters=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_constructor_declaration_throws=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_enum_constant_arguments=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_enum_declarations=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_explicitconstructorcall_arguments=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_for_increments=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_for_inits=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_method_declaration_parameters=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_method_declaration_throws=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_method_invocation_arguments=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_multiple_field_declarations=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_multiple_local_declarations=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_parameterized_type_reference=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_superinterfaces=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_switch_case_expressions=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_type_arguments=insert
-org.eclipse.jdt.core.formatter.insert_space_after_comma_in_type_parameters=insert
-org.eclipse.jdt.core.formatter.insert_space_after_ellipsis=insert
-org.eclipse.jdt.core.formatter.insert_space_after_lambda_arrow=insert
-org.eclipse.jdt.core.formatter.insert_space_after_logical_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_after_multiplicative_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_after_not_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_angle_bracket_in_parameterized_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_angle_bracket_in_type_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_angle_bracket_in_type_parameters=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_brace_in_array_initializer=insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_bracket_in_array_allocation_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_bracket_in_array_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_annotation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_cast=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_catch=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_constructor_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_enum_constant=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_for=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_if=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_method_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_method_invocation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_parenthesized_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_switch=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_synchronized=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_try=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_opening_paren_in_while=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_postfix_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_prefix_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_question_in_conditional=insert
-org.eclipse.jdt.core.formatter.insert_space_after_question_in_wildcard=do not insert
-org.eclipse.jdt.core.formatter.insert_space_after_relational_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_after_semicolon_in_for=insert
-org.eclipse.jdt.core.formatter.insert_space_after_semicolon_in_try_resources=insert
-org.eclipse.jdt.core.formatter.insert_space_after_shift_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_after_string_concatenation=insert
-org.eclipse.jdt.core.formatter.insert_space_after_unary_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_additive_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_and_in_type_parameter=insert
-org.eclipse.jdt.core.formatter.insert_space_before_arrow_in_switch_case=insert
-org.eclipse.jdt.core.formatter.insert_space_before_arrow_in_switch_default=insert
-org.eclipse.jdt.core.formatter.insert_space_before_assignment_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_at_in_annotation_type_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_bitwise_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_angle_bracket_in_parameterized_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_angle_bracket_in_type_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_angle_bracket_in_type_parameters=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_brace_in_array_initializer=insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_bracket_in_array_allocation_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_bracket_in_array_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_annotation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_cast=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_catch=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_constructor_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_enum_constant=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_for=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_if=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_method_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_method_invocation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_parenthesized_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_switch=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_synchronized=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_try=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_closing_paren_in_while=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_colon_in_assert=insert
-org.eclipse.jdt.core.formatter.insert_space_before_colon_in_case=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_colon_in_conditional=insert
-org.eclipse.jdt.core.formatter.insert_space_before_colon_in_default=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_colon_in_for=insert
-org.eclipse.jdt.core.formatter.insert_space_before_colon_in_labeled_statement=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_allocation_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_annotation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_array_initializer=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_constructor_declaration_parameters=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_constructor_declaration_throws=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_enum_constant_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_enum_declarations=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_explicitconstructorcall_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_for_increments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_for_inits=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_method_declaration_parameters=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_method_declaration_throws=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_method_invocation_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_multiple_field_declarations=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_multiple_local_declarations=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_parameterized_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_superinterfaces=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_switch_case_expressions=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_type_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_comma_in_type_parameters=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_ellipsis=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_lambda_arrow=insert
-org.eclipse.jdt.core.formatter.insert_space_before_logical_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_multiplicative_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_angle_bracket_in_parameterized_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_angle_bracket_in_type_arguments=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_angle_bracket_in_type_parameters=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_annotation_type_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_anonymous_type_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_array_initializer=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_block=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_constructor_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_enum_constant=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_enum_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_method_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_switch=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_brace_in_type_declaration=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_bracket_in_array_allocation_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_bracket_in_array_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_bracket_in_array_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_annotation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_annotation_type_member_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_catch=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_constructor_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_enum_constant=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_for=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_if=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_method_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_method_invocation=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_parenthesized_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_switch=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_synchronized=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_try=insert
-org.eclipse.jdt.core.formatter.insert_space_before_opening_paren_in_while=insert
-org.eclipse.jdt.core.formatter.insert_space_before_parenthesized_expression_in_return=insert
-org.eclipse.jdt.core.formatter.insert_space_before_parenthesized_expression_in_throw=insert
-org.eclipse.jdt.core.formatter.insert_space_before_postfix_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_prefix_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_question_in_conditional=insert
-org.eclipse.jdt.core.formatter.insert_space_before_question_in_wildcard=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_relational_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_semicolon=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_semicolon_in_for=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_semicolon_in_try_resources=do not insert
-org.eclipse.jdt.core.formatter.insert_space_before_shift_operator=insert
-org.eclipse.jdt.core.formatter.insert_space_before_string_concatenation=insert
-org.eclipse.jdt.core.formatter.insert_space_before_unary_operator=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_brackets_in_array_type_reference=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_braces_in_array_initializer=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_brackets_in_array_allocation_expression=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_annotation_type_member_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_constructor_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_enum_constant=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_method_declaration=do not insert
-org.eclipse.jdt.core.formatter.insert_space_between_empty_parens_in_method_invocation=do not insert
-org.eclipse.jdt.core.formatter.join_lines_in_comments=false
-org.eclipse.jdt.core.formatter.join_wrapped_lines=true
-org.eclipse.jdt.core.formatter.keep_annotation_declaration_on_one_line=one_line_if_single_item
-org.eclipse.jdt.core.formatter.keep_anonymous_type_declaration_on_one_line=one_line_never
-org.eclipse.jdt.core.formatter.keep_code_block_on_one_line=one_line_if_empty
-org.eclipse.jdt.core.formatter.keep_else_statement_on_same_line=true
-org.eclipse.jdt.core.formatter.keep_empty_array_initializer_on_one_line=false
-org.eclipse.jdt.core.formatter.keep_enum_constant_declaration_on_one_line=one_line_never
-org.eclipse.jdt.core.formatter.keep_enum_declaration_on_one_line=one_line_if_empty
-org.eclipse.jdt.core.formatter.keep_if_then_body_block_on_one_line=one_line_if_single_item
-org.eclipse.jdt.core.formatter.keep_imple_if_on_one_line=false
-org.eclipse.jdt.core.formatter.keep_lambda_body_block_on_one_line=one_line_always
-org.eclipse.jdt.core.formatter.keep_loop_body_block_on_one_line=one_line_if_empty
-org.eclipse.jdt.core.formatter.keep_method_body_on_one_line=one_line_if_single_item
-org.eclipse.jdt.core.formatter.keep_simple_do_while_body_on_same_line=false
-org.eclipse.jdt.core.formatter.keep_simple_for_body_on_same_line=false
-org.eclipse.jdt.core.formatter.keep_simple_getter_setter_on_one_line=true
-org.eclipse.jdt.core.formatter.keep_simple_while_body_on_same_line=false
-org.eclipse.jdt.core.formatter.keep_then_statement_on_same_line=true
-org.eclipse.jdt.core.formatter.keep_type_declaration_on_one_line=one_line_if_empty
-org.eclipse.jdt.core.formatter.lineSplit=150
-org.eclipse.jdt.core.formatter.never_indent_block_comments_on_first_column=false
-org.eclipse.jdt.core.formatter.never_indent_line_comments_on_first_column=false
-org.eclipse.jdt.core.formatter.number_of_blank_lines_after_code_block=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_at_beginning_of_code_block=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_at_beginning_of_method_body=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_at_end_of_code_block=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_at_end_of_method_body=0
-org.eclipse.jdt.core.formatter.number_of_blank_lines_before_code_block=0
-org.eclipse.jdt.core.formatter.number_of_empty_lines_to_preserve=1
-org.eclipse.jdt.core.formatter.parentheses_positions_in_annotation=separate_lines_if_wrapped
-org.eclipse.jdt.core.formatter.parentheses_positions_in_catch_clause=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_enum_constant_declaration=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_for_statment=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_if_while_statement=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_lambda_declaration=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_method_delcaration=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_method_invocation=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_switch_statement=common_lines
-org.eclipse.jdt.core.formatter.parentheses_positions_in_try_clause=common_lines
-org.eclipse.jdt.core.formatter.put_empty_statement_on_new_line=true
-org.eclipse.jdt.core.formatter.tabulation.char=tab
-org.eclipse.jdt.core.formatter.tabulation.size=4
-org.eclipse.jdt.core.formatter.text_block_indentation=0
-org.eclipse.jdt.core.formatter.use_on_off_tags=false
-org.eclipse.jdt.core.formatter.use_tabs_only_for_leading_indentations=false
-org.eclipse.jdt.core.formatter.wrap_before_additive_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_assignment_operator=false
-org.eclipse.jdt.core.formatter.wrap_before_bitwise_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_conditional_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_logical_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_multiplicative_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_or_operator_multicatch=true
-org.eclipse.jdt.core.formatter.wrap_before_relational_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_shift_operator=true
-org.eclipse.jdt.core.formatter.wrap_before_string_concatenation=true
-org.eclipse.jdt.core.formatter.wrap_outer_expressions_when_nested=true
 org.eclipse.jdt.core.javaFormatter=org.eclipse.jdt.core.defaultJavaFormatter

common/pom.xml

@@ -12,18 +12,11 @@
 		<version>0.2-beta</version>
 	</parent>
 
-	<repositories>
-		<repository>
-			<id>kske-repo</id>
-			<url>https://kske.dev/maven-repo</url>
-		</repository>
-	</repositories>
-
 	<dependencies>
 		<dependency>
 			<groupId>dev.kske</groupId>
-			<artifactId>event-bus</artifactId>
-			<version>0.0.4</version>
+			<artifactId>event-bus-core</artifactId>
+			<version>1.0.0</version>
 		</dependency>
 		<dependency>
 			<groupId>org.junit.jupiter</groupId>

common/src/main/java/envoy/data/Attachment.java

@@ -1,10 +1,11 @@
 package envoy.data;
 
 import java.io.Serializable;
+import java.util.Objects;
 
 /**
- * This interface should be used for any type supposed to be a {@link Message}
- * attachment (i.e. images or sound).
+ * This interface should be used for any type supposed to be a {@link Message} attachment (i.e.
+ * images or sound).
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart
@@ -63,9 +64,9 @@ public final class Attachment implements Serializable {
 	 * @since Envoy Common v0.1-beta
 	 */
 	public Attachment(byte[] data, String name, AttachmentType type) {
-		this.data	= data;
-		this.name	= name;
-		this.type	= type;
+		this.data	= Objects.requireNonNull(data);
+		this.name	= Objects.requireNonNull(name);
+		this.type	= Objects.requireNonNull(type);
 	}
 
 	/**

common/src/main/java/envoy/data/Config.java

@@ -9,15 +9,13 @@ import java.util.stream.Collectors;
 import envoy.util.EnvoyLog;
 
 /**
- * Manages all application settings that are set during application startup by
- * either loading them from the {@link Properties} file (default values)
- * {@code client.properties} or parsing them from the command line arguments of
- * the application.
+ * Manages all application settings that are set during application startup by either loading them
+ * from the {@link Properties} file (default values) {@code client.properties} or parsing them from
+ * the command line arguments of the application.
  * <p>
- * All items inside the {@code Config} are supposed to either be supplied over
- * default value or over command line argument. Developers that fail to provide
- * default values will be greeted with an error message the next time they try
- * to start Envoy...
+ * All items inside the {@code Config} are supposed to either be supplied over default value or over
+ * command line argument. Developers that fail to provide default values will be greeted with an
+ * error message the next time they try to start Envoy...
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.1-beta
@@ -51,8 +49,7 @@ public class Config {
 	 * Parses config items from an array of command line arguments.
 	 *
 	 * @param args the command line arguments to parse
-	 * @throws IllegalStateException if a malformed command line argument has been
-	 *                               supplied
+	 * @throws IllegalStateException if a malformed command line argument has been supplied
 	 * @since Envoy Common v0.1-beta
 	 */
 	private void load(String[] args) {
@@ -82,30 +79,31 @@ public class Config {
 	}
 
 	/**
-	 * Supplies default values from the given .properties file and parses the
-	 * configuration from an array of command line arguments.
+	 * Supplies default values from the given .properties file and parses the configuration from an
+	 * array of command line arguments.
 	 *
 	 * @param declaringClass     the class calling this method
-	 * @param propertiesFilePath the path to where the .properties file can be found
-	 *                           - will be only the file name if it is located
-	 *                           directly inside the {@code src/main/resources}
-	 *                           folder
+	 * @param propertiesFilePath the path to where the .properties file can be found - will be only
+	 *                           the file name if it is located directly inside the
+	 *                           {@code src/main/resources} folder
 	 * @param args               the command line arguments to parse
-	 * @throws IllegalStateException if this method is getting called again or if a
-	 *                               malformed command line argument has been
-	 *                               supplied
+	 * @throws IllegalStateException if this method is getting called again or if a malformed
+	 *                               command line argument has been supplied
 	 * @since Envoy Common v0.1-beta
 	 */
 	public void loadAll(Class<?> declaringClass, String propertiesFilePath, String[] args) {
 		if (modificationDisabled)
-			throw new IllegalStateException("Cannot change config after isInitialized has been called");
+			throw new IllegalStateException(
+				"Cannot change config after isInitialized has been called");
 
 		// Load the defaults from the given .properties file first
 		final var properties = new Properties();
 		try {
-			properties.load(declaringClass.getClassLoader().getResourceAsStream(propertiesFilePath));
+			properties
+				.load(declaringClass.getClassLoader().getResourceAsStream(propertiesFilePath));
 		} catch (final IOException e) {
-			EnvoyLog.getLogger(Config.class).log(Level.SEVERE, "An error occurred when reading in the configuration: ",
+			EnvoyLog.getLogger(Config.class).log(Level.SEVERE,
+				"An error occurred when reading in the configuration: ",
 				e);
 		}
 		load(properties);
@@ -122,13 +120,13 @@ public class Config {
 	}
 
 	/**
-	 * @throws IllegalStateException if a {@link ConfigItem} has not been
-	 *                               initialized
+	 * @throws IllegalStateException if a {@link ConfigItem} has not been initialized
 	 * @since Envoy Common v0.1-beta
 	 */
 	private void isInitialized() {
-		String uninitialized = items.values().stream().filter(c -> c.get() == null).map(ConfigItem::getCommandLong).collect(Collectors.joining(", "));
-		if(!uninitialized.isEmpty())
+		String uninitialized = items.values().stream().filter(c -> c.get() == null)
+			.map(ConfigItem::getCommandLong).collect(Collectors.joining(", "));
+		if (!uninitialized.isEmpty())
 			throw new IllegalStateException("Config items uninitialized: " + uninitialized);
 	}
 
@@ -148,11 +146,11 @@ public class Config {
 	 * @param <T>           the type of the {@link ConfigItem}
 	 * @param commandName   the key for this config item as well as its long name
 	 * @param commandShort  the abbreviation of this config item
-	 * @param parseFunction the {@code Function<String, T>} that parses the value
-	 *                      from a string
+	 * @param parseFunction the {@code Function<String, T>} that parses the value from a string
 	 * @since Envoy Common v0.2-beta
 	 */
-	protected <T> void put(String commandName, String commandShort, Function<String, T> parseFunction) {
+	protected <T> void put(String commandName, String commandShort,
+		Function<String, T> parseFunction) {
 		items.put(commandName, new ConfigItem<>(commandName, commandShort, parseFunction));
 	}
 
@@ -160,17 +158,13 @@ public class Config {
 	 * @return the directory in which all local files are saves
 	 * @since Envoy Client v0.2-beta
 	 */
-	public File getHomeDirectory() {
-		return (File) items.get("homeDirectory").get();
-	}
+	public File getHomeDirectory() { return (File) items.get("homeDirectory").get(); }
 
 	/**
 	 * @return the minimal {@link Level} to log inside the log file
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Level getFileLevelBarrier() {
-		return (Level) items.get("fileLevelBarrier").get();
-	}
+	public Level getFileLevelBarrier() { return (Level) items.get("fileLevelBarrier").get(); }
 
 	/**
 	 * @return the minimal {@link Level} to log inside the console

common/src/main/java/envoy/data/ConfigItem.java

@@ -3,8 +3,8 @@ package envoy.data;
 import java.util.function.Function;
 
 /**
- * Contains a single {@link Config} value as well as the corresponding command
- * line arguments and its default value.
+ * Contains a single {@link Config} value as well as the corresponding command line arguments and
+ * its default value.
  * <p>
  * All {@code ConfigItem}s are automatically mandatory.
  *
@@ -24,8 +24,7 @@ public final class ConfigItem<T> {
 	 *
 	 * @param commandLong   the long command line argument to set this value
 	 * @param commandShort  the short command line argument to set this value
-	 * @param parseFunction the {@code Function<String, T>} that parses the value
-	 *                      from a string
+	 * @param parseFunction the {@code Function<String, T>} that parses the value from a string
 	 * @since Envoy Common v0.1-beta
 	 */
 	public ConfigItem(String commandLong, String commandShort, Function<String, T> parseFunction) {
@@ -40,18 +39,18 @@ public final class ConfigItem<T> {
 	 * @param input the string to parse from
 	 * @since Envoy Common v0.1-beta
 	 */
-	public void parse(String input) { value = parseFunction.apply(input); }
+	public void parse(String input) {
+		value = parseFunction.apply(input);
+	}
 
 	/**
-	 * @return The long command line argument to set the value of this
-	 *         {@link ConfigItem}
+	 * @return The long command line argument to set the value of this {@link ConfigItem}
 	 * @since Envoy Common v0.1-beta
 	 */
 	public String getCommandLong() { return commandLong; }
 
 	/**
-	 * @return The short command line argument to set the value of this
-	 *         {@link ConfigItem}
+	 * @return The short command line argument to set the value of this {@link ConfigItem}
 	 * @since Envoy Common v0.1-beta
 	 */
 	public String getCommandShort() { return commandShort; }
@@ -60,7 +59,9 @@ public final class ConfigItem<T> {
 	 * @return the value of this {@link ConfigItem}
 	 * @since Envoy Common v0.1-beta
 	 */
-	public T get() { return value; }
+	public T get() {
+		return value;
+	}
 
 	/**
 	 * @param value the value to set

common/src/main/java/envoy/data/Contact.java

@@ -29,8 +29,8 @@ public abstract class Contact implements Serializable {
 	 */
 	public Contact(long id, String name, Set<? extends Contact> contacts) {
 		this.id			= id;
-		this.name		= name;
-		this.contacts	= contacts;
+		this.name		= Objects.requireNonNull(name);
+		this.contacts	= contacts == null ? new HashSet<>() : contacts;
 	}
 
 	/**
@@ -57,19 +57,23 @@ public abstract class Contact implements Serializable {
 	 * @since Envoy Common v0.1-beta
 	 */
 	@Override
-	public final int hashCode() { return Objects.hash(id); }
+	public final int hashCode() {
+		return Objects.hash(id);
+	}
 
 	/**
-	 * Tests equality to another object. If that object is a contact as well,
-	 * equality is determined by the ID.
+	 * Tests equality to another object. If that object is a contact as well, equality is determined
+	 * by the ID.
 	 *
 	 * @param obj the object to test for equality to this contact
 	 * @return {code true} if both objects are contacts and have identical IDs
 	 */
 	@Override
 	public final boolean equals(Object obj) {
-		if (this == obj) return true;
-		if (!(obj instanceof Contact)) return false;
+		if (this == obj)
+			return true;
+		if (!(obj instanceof Contact))
+			return false;
 		return id == ((Contact) obj).id;
 	}
 

common/src/main/java/envoy/data/Group.java

@@ -18,7 +18,9 @@ public final class Group extends Contact {
 	 * @param name the name of this group
 	 * @since Envoy Common v0.1-beta
 	 */
-	public Group(long id, String name) { this(id, name, new HashSet<User>()); }
+	public Group(long id, String name) {
+		this(id, name, new HashSet<User>());
+	}
 
 	/**
 	 * Creates an instance of a {@link Group}.
@@ -28,10 +30,14 @@ public final class Group extends Contact {
 	 * @param members all members that should be preinitialized
 	 * @since Envoy Common v0.1-beta
 	 */
-	public Group(long id, String name, Set<User> members) { super(id, name, members); }
+	public Group(long id, String name, Set<User> members) {
+		super(id, name, members);
+	}
 
 	@Override
-	public String toString() { return String.format("Group[id=%d,name=%s,%d member(s)]", id, name, contacts.size()); }
+	public String toString() {
+		return String.format("Group[id=%d,name=%s,%d member(s)]", id, name, contacts.size());
+	}
 
 	private void readObject(ObjectInputStream inputStream) throws Exception {
 		inputStream.defaultReadObject();

common/src/main/java/envoy/data/GroupMessage.java

@@ -14,11 +14,9 @@ public final class GroupMessage extends Message {
 	private static final long serialVersionUID = 1L;
 
 	/**
-	 * Initializes a {@link GroupMessage} with values for all of its properties. The
-	 * use
-	 * of this constructor is only intended for the {@link MessageBuilder} class, as
-	 * this class provides {@code null} checks and default values for all
-	 * properties.
+	 * Initializes a {@link GroupMessage} with values for all of its properties. The use of this
+	 * constructor is only intended for the {@link MessageBuilder} class, as this class provides
+	 * {@code null} checks and default values for all properties.
 	 *
 	 * @param id             unique ID
 	 * @param senderID       the ID of the user who sends the message
@@ -28,17 +26,20 @@ public final class GroupMessage extends Message {
 	 * @param readDate       the read date of the message
 	 * @param text           the text content of the message
 	 * @param attachment     the attachment of the message, if present
-	 * @param status         the current {@link Message.MessageStatus} of the
-	 *                       message
+	 * @param status         the current {@link Message.MessageStatus} of the message
 	 * @param forwarded      whether this message was forwarded
 	 * @param memberStatuses a map of all members and their status according to this
 	 *                       {@link GroupMessage}
 	 * @since Envoy Common v0.2-beta
 	 */
-	GroupMessage(long id, long senderID, long groupID, Instant creationDate, Instant receivedDate, Instant readDate, String text,
-			Attachment attachment, MessageStatus status, boolean forwarded, Map<Long, MessageStatus> memberStatuses) {
-		super(id, senderID, groupID, creationDate, receivedDate, readDate, text, attachment, status, forwarded);
-		this.memberStatuses = memberStatuses;
+	GroupMessage(long id, long senderID, long groupID, Instant creationDate, Instant receivedDate,
+		Instant readDate, String text,
+		Attachment attachment, MessageStatus status, boolean forwarded,
+		Map<Long, MessageStatus> memberStatuses) {
+		super(id, senderID, groupID, creationDate, receivedDate, readDate, text, attachment, status,
+			forwarded);
+		this.memberStatuses =
+			memberStatuses == null ? new HashMap<>() : memberStatuses;
 	}
 
 	/**

common/src/main/java/envoy/data/IDGenerator.java

@@ -2,15 +2,13 @@ package envoy.data;
 
 import java.io.Serializable;
 
-import dev.kske.eventbus.IEvent;
-
 /**
  * Generates increasing IDs between two numbers.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.2-alpha
  */
-public final class IDGenerator implements IEvent, Serializable {
+public final class IDGenerator implements Serializable {
 
 	private final long	end;
 	private long		current;
@@ -30,20 +28,25 @@ public final class IDGenerator implements IEvent, Serializable {
 	}
 
 	@Override
-	public String toString() { return String.format("IDGenerator[current=%d,end=%d]", current, end); }
+	public String toString() {
+		return String.format("IDGenerator[current=%d,end=%d]", current, end);
+	}
 
 	/**
 	 * @return {@code true} if there are unused IDs remaining
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public boolean hasNext() { return current < end; }
+	public boolean hasNext() {
+		return current < end;
+	}
 
 	/**
 	 * @return the next ID
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public long next() {
-		if (!hasNext()) throw new IllegalStateException("All IDs have been used");
+		if (!hasNext())
+			throw new IllegalStateException("All IDs have been used");
 		return current++;
 	}
 }

common/src/main/java/envoy/data/LoginCredentials.java

@@ -2,13 +2,12 @@ package envoy.data;
 
 import java.io.Serializable;
 import java.time.Instant;
+import java.util.Objects;
 
 /**
- * Contains a {@link User}'s login / registration information as well as the
- * client version.
+ * Contains a {@link User}'s login / registration information as well as the client version.
  * <p>
- * If the authentication is performed with a token, the token is stored instead
- * of the password.
+ * If the authentication is performed with a token, the token is stored instead of the password.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.2-alpha
@@ -21,15 +20,15 @@ public final class LoginCredentials implements Serializable {
 
 	private static final long serialVersionUID = 4;
 
-	private LoginCredentials(String identifier, String password, boolean registration, boolean token, boolean requestToken, String clientVersion,
-			Instant lastSync) {
-		this.identifier		= identifier;
-		this.password		= password;
+	private LoginCredentials(String identifier, String password, boolean registration,
+		boolean token, boolean requestToken, String clientVersion, Instant lastSync) {
+		this.identifier		= Objects.requireNonNull(identifier);
+		this.password		= Objects.requireNonNull(password);
 		this.registration	= registration;
 		this.token			= token;
 		this.requestToken	= requestToken;
-		this.clientVersion	= clientVersion;
-		this.lastSync		= lastSync;
+		this.clientVersion	= Objects.requireNonNull(clientVersion);
+		this.lastSync		= lastSync == null ? Instant.EPOCH : lastSync;
 	}
 
 	/**
@@ -43,8 +42,10 @@ public final class LoginCredentials implements Serializable {
 	 * @return the created login credentials
 	 * @since Envoy Common v0.2-beta
 	 */
-	public static LoginCredentials login(String identifier, String password, boolean requestToken, String clientVersion, Instant lastSync) {
-		return new LoginCredentials(identifier, password, false, false, requestToken, clientVersion, lastSync);
+	public static LoginCredentials login(String identifier, String password, boolean requestToken,
+		String clientVersion, Instant lastSync) {
+		return new LoginCredentials(identifier, password, false, false, requestToken, clientVersion,
+			lastSync);
 	}
 
 	/**
@@ -57,7 +58,8 @@ public final class LoginCredentials implements Serializable {
 	 * @return the created login credentials
 	 * @since Envoy Common v0.2-beta
 	 */
-	public static LoginCredentials loginWithToken(String identifier, String token, String clientVersion, Instant lastSync) {
+	public static LoginCredentials loginWithToken(String identifier, String token,
+		String clientVersion, Instant lastSync) {
 		return new LoginCredentials(identifier, token, false, true, false, clientVersion, lastSync);
 	}
 
@@ -72,13 +74,17 @@ public final class LoginCredentials implements Serializable {
 	 * @return the created login credentials
 	 * @since Envoy Common v0.2-beta
 	 */
-	public static LoginCredentials registration(String identifier, String password, boolean requestToken, String clientVersion, Instant lastSync) {
-		return new LoginCredentials(identifier, password, true, false, requestToken, clientVersion, lastSync);
+	public static LoginCredentials registration(String identifier, String password,
+		boolean requestToken,
+		String clientVersion, Instant lastSync) {
+		return new LoginCredentials(identifier, password, true, false, requestToken, clientVersion,
+			lastSync);
 	}
 
 	@Override
 	public String toString() {
-		return String.format("LoginCredentials[identifier=%s,registration=%b,token=%b,requestToken=%b,clientVersion=%s,lastSync=%s]",
+		return String.format(
+			"LoginCredentials[identifier=%s,registration=%b,token=%b,requestToken=%b,clientVersion=%s,lastSync=%s]",
 			identifier,
 			registration,
 			token,
@@ -100,24 +106,27 @@ public final class LoginCredentials implements Serializable {
 	public String getPassword() { return password; }
 
 	/**
-	 * @return {@code true} if these credentials are used for user registration
-	 *         instead of user login
+	 * @return {@code true} if these credentials are used for user registration instead of user
+	 *         login
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public boolean isRegistration() { return registration; }
 
 	/**
-	 * @return {@code true} if these credentials use an authentication token instead
-	 *         of a password
+	 * @return {@code true} if these credentials use an authentication token instead of a password
 	 * @since Envoy Common v0.2-beta
 	 */
-	public boolean usesToken() { return token; }
+	public boolean usesToken() {
+		return token;
+	}
 
 	/**
 	 * @return {@code true} if the server should generate a new authentication token
 	 * @since Envoy Common v0.2-beta
 	 */
-	public boolean requestToken() { return requestToken; }
+	public boolean requestToken() {
+		return requestToken;
+	}
 
 	/**
 	 * @return the version of the client sending these credentials

common/src/main/java/envoy/data/Message.java

@@ -2,19 +2,17 @@ package envoy.data;
 
 import java.io.Serializable;
 import java.time.Instant;
-
-import dev.kske.eventbus.IEvent;
+import java.util.Objects;
 
 /**
- * Represents a unique message with a unique, numeric ID. Further metadata
- * includes the sender and recipient {@link User}s, as well as the creation
- * date and the current {@link MessageStatus}.<br>
+ * Represents a unique message with a unique, numeric ID. Further metadata includes the sender and
+ * recipient {@link User}s, as well as the creation date and the current {@link MessageStatus}.<br>
  *
  * @author Kai S. K. Engelbart
  * @author Leon Hofmeister
  * @since Envoy Common v0.2-alpha
  */
-public class Message implements Serializable, IEvent {
+public class Message implements Serializable {
 
 	/**
 	 * This enumeration defines all possible statuses a {link Message} can have.
@@ -56,10 +54,9 @@ public class Message implements Serializable, IEvent {
 	private static final long serialVersionUID = 2L;
 
 	/**
-	 * Initializes a {@link Message} with values for all of its properties. The use
-	 * of this constructor is only intended for the {@link MessageBuilder} class, as
-	 * this class provides {@code null} checks and default values for all
-	 * properties.
+	 * Initializes a {@link Message} with values for all of its properties. The use of this
+	 * constructor is only intended for the {@link MessageBuilder} class, as this class provides
+	 * {@code null} checks and default values for all properties.
 	 *
 	 * @param id           unique ID
 	 * @param senderID     the ID of the user who sends the message
@@ -73,7 +70,8 @@ public class Message implements Serializable, IEvent {
 	 * @param forwarded    whether this message was forwarded
 	 * @since Envoy Common v0.2-beta
 	 */
-	Message(long id, long senderID, long recipientID, Instant creationDate, Instant receivedDate, Instant readDate, String text,
+	Message(long id, long senderID, long recipientID, Instant creationDate, Instant receivedDate,
+		Instant readDate, String text,
 		Attachment attachment, MessageStatus status, boolean forwarded) {
 		this.id				= id;
 		this.senderID		= senderID;
@@ -81,9 +79,9 @@ public class Message implements Serializable, IEvent {
 		this.creationDate	= creationDate;
 		this.receivedDate	= receivedDate;
 		this.readDate		= readDate;
-		this.text			= text;
+		this.text			= text == null ? "" : text;
 		this.attachment		= attachment;
-		this.status			= status;
+		this.status			= Objects.requireNonNull(status);
 		this.forwarded		= forwarded;
 	}
 
@@ -101,13 +99,15 @@ public class Message implements Serializable, IEvent {
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public void nextStatus() {
-		if (status == MessageStatus.READ) throw new IllegalStateException("Message status READ is already reached");
+		if (status == MessageStatus.READ)
+			throw new IllegalStateException("Message status READ is already reached");
 		status = MessageStatus.values()[status.ordinal() + 1];
 	}
 
 	@Override
 	public String toString() {
-		return String.format("Message[id=%d,sender=%s,recipient=%s,date=%s,status=%s,text=%s,forwarded=%b,hasAttachment=%b]",
+		return String.format(
+			"Message[id=%d,sender=%s,recipient=%s,date=%s,status=%s,text=%s,forwarded=%b,hasAttachment=%b]",
 			id,
 			senderID,
 			recipientID,
@@ -149,8 +149,7 @@ public class Message implements Serializable, IEvent {
 	public Instant getReceivedDate() { return receivedDate; }
 
 	/**
-	 * @param receivedDate the date at which the message has been received by the
-	 *                     sender
+	 * @param receivedDate the date at which the message has been received by the sender
 	 * @since Envoy Common v0.2-beta
 	 */
 	public void setReceivedDate(Instant receivedDate) { this.receivedDate = receivedDate; }
@@ -183,7 +182,9 @@ public class Message implements Serializable, IEvent {
 	 * @return {@code true} if an attachment is present
 	 * @since Envoy Common v0.1-beta
 	 */
-	public boolean hasAttachment() { return attachment != null; }
+	public boolean hasAttachment() {
+		return attachment != null;
+	}
 
 	/**
 	 * @return the current status of this message
@@ -196,7 +197,8 @@ public class Message implements Serializable, IEvent {
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public void setStatus(MessageStatus status) {
-		if (status.ordinal() < this.status.ordinal()) throw new IllegalStateException("This message is moving backwards in time");
+		if (status.ordinal() < this.status.ordinal())
+			throw new IllegalStateException("This message is moving backwards in time");
 		this.status = status;
 	}
 

common/src/main/java/envoy/data/MessageBuilder.java

@@ -25,20 +25,21 @@ public final class MessageBuilder {
 	private boolean					forwarded;
 
 	/**
-	 * Creates an instance of {@link MessageBuilder} with all mandatory values
-	 * without defaults for the {@link Message} class.
+	 * Creates an instance of {@link MessageBuilder} with all mandatory values without defaults for
+	 * the {@link Message} class.
 	 *
 	 * @param senderID    the ID of the user who sends the {@link Message}
 	 * @param recipientID the ID of the user who receives the {@link Message}
-	 * @param idGenerator the ID generator used to generate a unique {@link Message}
-	 *                    id
+	 * @param idGenerator the ID generator used to generate a unique {@link Message} id
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public MessageBuilder(long senderID, long recipientID, IDGenerator idGenerator) { this(senderID, recipientID, idGenerator.next()); }
+	public MessageBuilder(long senderID, long recipientID, IDGenerator idGenerator) {
+		this(senderID, recipientID, idGenerator.next());
+	}
 
 	/**
-	 * Creates an instance of {@link MessageBuilder} with all mandatory values
-	 * without defaults for the {@link Message} class.
+	 * Creates an instance of {@link MessageBuilder} with all mandatory values without defaults for
+	 * the {@link Message} class.
 	 *
 	 * @param senderID    the ID of the user who sends the {@link Message}
 	 * @param recipientID the ID of the user who receives the {@link Message}
@@ -52,14 +53,12 @@ public final class MessageBuilder {
 	}
 
 	/**
-	 * This constructor transforms a given {@link Message} into a new message for a
-	 * new receiver.
+	 * This constructor transforms a given {@link Message} into a new message for a new receiver.
 	 * This makes it especially useful in the case of forwarding messages.
 	 *
 	 * @param msg         the message to copy
 	 * @param recipientID the ID of the user who receives the {@link Message}
-	 * @param iDGenerator the ID generator used to generate a unique {@link Message}
-	 *                    id
+	 * @param iDGenerator the ID generator used to generate a unique {@link Message} id
 	 * @since Envoy v0.1-beta
 	 */
 	public MessageBuilder(Message msg, long recipientID, IDGenerator iDGenerator) {
@@ -72,79 +71,69 @@ public final class MessageBuilder {
 	}
 
 	/**
-	 * Creates an instance of {@link Message} with the previously supplied values.
-	 * If a mandatory value is not set, a default value will be used instead:<br>
+	 * Creates an instance of {@link Message} with the previously supplied values. If a mandatory
+	 * value is not set, a default value will be used instead:<br>
 	 * <br>
-	 * {@code date}
-	 * {@code Instant.now()} and {@code null} for {@code receivedDate} and
-	 * {@code readDate}
-	 * <br>
-	 * {@code text}
-	 * {@code ""}
-	 * <br>
-	 * {@code status}
-	 * {@code MessageStatus.WAITING}
+	 * {@code date} {@code Instant.now()} and {@code null} for {@code receivedDate} and
+	 * {@code readDate} <br>
+	 * {@code text} {@code ""} <br>
+	 * {@code status} {@code MessageStatus.WAITING}
 	 *
 	 * @return a new instance of {@link Message}
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public Message build() {
 		supplyDefaults();
-		return new Message(id, senderID, recipientID, creationDate, receivedDate, readDate, text, attachment, status, forwarded);
+		return new Message(id, senderID, recipientID, creationDate, receivedDate, readDate, text,
+			attachment, status, forwarded);
 	}
 
 	/**
-	 * Creates an instance of {@link GroupMessage} with the previously supplied
-	 * values. <br>
+	 * Creates an instance of {@link GroupMessage} with the previously supplied values. <br>
 	 * <b> Sets all member statuses to {@link MessageStatus#WAITING}.</b><br>
-	 * If a mandatory value is not set, a default value will be used
-	 * instead:<br>
-	 * <br>
-	 * {@code time stamp}
-	 * {@code Instant.now()}
-	 * <br>
-	 * {@code text}
-	 * {@code ""}
+	 * If a mandatory value is not set, a default value will be used instead:<br>
 	 * <br>
+	 * {@code time stamp} {@code Instant.now()} <br>
+	 * {@code text} {@code ""} <br>
 	 *
-	 * @param group the {@link Group} that is used to fill the map of member
-	 *              statuses
+	 * @param group the {@link Group} that is used to fill the map of member statuses
 	 * @return a new instance of {@link GroupMessage}
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public GroupMessage buildGroupMessage(Group group) {
 		final var memberStatuses = new HashMap<Long, Message.MessageStatus>();
-		group.getContacts().forEach(user -> memberStatuses.put(user.getID(), MessageStatus.WAITING));
+		group.getContacts()
+			.forEach(user -> memberStatuses.put(user.getID(), MessageStatus.WAITING));
 		return buildGroupMessage(group, memberStatuses);
 	}
 
 	/**
-	 * Creates an instance of {@link GroupMessage} with the previously supplied
-	 * values. If a mandatory value is not set, a default value will be used
-	 * instead:<br>
+	 * Creates an instance of {@link GroupMessage} with the previously supplied values. If a
+	 * mandatory value is not set, a default value will be used instead:<br>
 	 * <br>
-	 * {@code time stamp}
-	 * {@code Instant.now()}
-	 * <br>
-	 * {@code text}
-	 * {@code ""}
+	 * {@code time stamp} {@code Instant.now()} <br>
+	 * {@code text} {@code ""}
 	 *
-	 * @param group          the {@link Group} that is used to fill the map of
-	 *                       member statuses
+	 * @param group          the {@link Group} that is used to fill the map of member statuses
 	 * @param memberStatuses the map of all current statuses
 	 * @return a new instance of {@link GroupMessage}
 	 * @since Envoy Common v0.1-beta
 	 */
 	public GroupMessage buildGroupMessage(Group group, Map<Long, MessageStatus> memberStatuses) {
-		if (group == null || memberStatuses == null) throw new NullPointerException();
+		if (group == null || memberStatuses == null)
+			throw new NullPointerException();
 		supplyDefaults();
-		return new GroupMessage(id, senderID, recipientID, creationDate, receivedDate, readDate, text, attachment, status, forwarded, memberStatuses);
+		return new GroupMessage(id, senderID, recipientID, creationDate, receivedDate, readDate,
+			text, attachment, status, forwarded, memberStatuses);
 	}
 
 	private void supplyDefaults() {
-		if (creationDate == null) creationDate = Instant.now();
-		if (text == null) text = "";
-		if (status == null) status = MessageStatus.WAITING;
+		if (creationDate == null)
+			creationDate = Instant.now();
+		if (text == null)
+			text = "";
+		if (status == null)
+			status = MessageStatus.WAITING;
 	}
 
 	/**
@@ -188,8 +177,7 @@ public final class MessageBuilder {
 	}
 
 	/**
-	 * @param attachment the {@link Attachment} of the {@link Message} to
-	 *                   create
+	 * @param attachment the {@link Attachment} of the {@link Message} to create
 	 * @return this {@link MessageBuilder}
 	 * @since Envoy Common v0.2-alpha
 	 */

common/src/main/java/envoy/data/User.java

@@ -4,8 +4,7 @@ import java.io.*;
 import java.util.*;
 
 /**
- * Represents a unique user with a unique, numeric ID, a name and a current
- * {@link UserStatus}.<br>
+ * Represents a unique user with a unique, numeric ID, a name and a current {@link UserStatus}.<br>
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.2-alpha
@@ -34,8 +33,7 @@ public final class User extends Contact {
 		ONLINE,
 
 		/**
-		 * select this, if a user is online but unavailable at the moment (sudden
-		 * interruption)
+		 * select this, if a user is online but unavailable at the moment (sudden interruption)
 		 */
 		AWAY,
 
@@ -52,8 +50,7 @@ public final class User extends Contact {
 
 	/**
 	 * Initializes a {@link User}. <br>
-	 * The {@link UserStatus} is set to {@link UserStatus#ONLINE}.
-	 * No contacts are initialized.
+	 * The {@link UserStatus} is set to {@link UserStatus#ONLINE}. No contacts are initialized.
 	 *
 	 * @param id   unique ID
 	 * @param name user name
@@ -89,12 +86,13 @@ public final class User extends Contact {
 	 */
 	public User(long id, String name, UserStatus status, Set<Contact> contacts) {
 		super(id, name, contacts);
-		this.status = status;
+		this.status = Objects.requireNonNull(status);
 	}
 
 	@Override
 	public String toString() {
-		return String.format("User[id=%d,name=%s,status=%s", id, name, status) + (contacts.isEmpty() ? "]" : "," + contacts.size() + " contact(s)]");
+		return String.format("User[id=%d,name=%s,status=%s", id, name, status)
+			+ (contacts.isEmpty() ? "]" : "," + contacts.size() + " contact(s)]");
 	}
 
 	/**
@@ -119,15 +117,18 @@ public final class User extends Contact {
 	private void writeObject(ObjectOutputStream outputStream) throws Exception {
 		outputStream.defaultWriteObject();
 		if (serializeContacts) {
-			getContacts().stream().filter(User.class::isInstance).map(User.class::cast).forEach(user -> user.serializeContacts = false);
+			getContacts().stream().filter(User.class::isInstance).map(User.class::cast)
+				.forEach(user -> user.serializeContacts = false);
 			outputStream.writeObject(getContacts());
-		} else outputStream.writeObject(new HashSet<>());
+		} else
+			outputStream.writeObject(new HashSet<>());
 	}
 
 	/**
-	 * @param serializeContacts whether the contacts of this {@link User} should be
-	 *                          serialized
+	 * @param serializeContacts whether the contacts of this {@link User} should be serialized
 	 * @since Envoy Common v0.1-beta
 	 */
-	public void serializeContacts(boolean serializeContacts) { this.serializeContacts = serializeContacts; }
+	public void serializeContacts(boolean serializeContacts) {
+		this.serializeContacts = serializeContacts;
+	}
 }

common/src/main/java/envoy/data/package-info.java

@@ -1,6 +1,5 @@
 /**
- * This package contains all data objects that are used both by Envoy Client and
- * by Envoy Server.
+ * This package contains all data objects that are used both by Envoy Client and by Envoy Server.
  *
  * @author Leon Hofmeister
  * @author Maximilian Käfer

common/src/main/java/envoy/event/ElementOperation.java

@@ -3,8 +3,7 @@ package envoy.event;
 /**
  * This enum declares all modification possibilities for a given container.
  * <p>
- * These can be: {@link ElementOperation#ADD} or
- * {@link ElementOperation#REMOVE}.
+ * These can be: {@link ElementOperation#ADD} or {@link ElementOperation#REMOVE}.
  *
  * @author Leon Hofmeister
  * @since Envoy Common v0.1-beta
@@ -12,14 +11,12 @@ package envoy.event;
 public enum ElementOperation {
 
 	/**
-	 * Select this element, if the given element should be added to the given
-	 * container.
+	 * Select this element, if the given element should be added to the given container.
 	 */
 	ADD,
 
 	/**
-	 * Select this element, if the given element should be removed from the given
-	 * container.
+	 * Select this element, if the given element should be removed from the given container.
 	 */
 	REMOVE
 }

common/src/main/java/envoy/event/Event.java

@@ -1,33 +1,46 @@
 package envoy.event;
 
 import java.io.Serializable;
-
-import dev.kske.eventbus.IEvent;
+import java.util.Objects;
 
 /**
- * This class serves as a convenience base class for all events. It implements
- * the {@link IEvent} interface and provides a generic value. For events without
- * a value there also is {@link envoy.event.Event.Valueless}.
+ * This class serves as a convenience base class for all events. It provides a generic value. For
+ * events without a value there also is {@link envoy.event.Event.Valueless}.
  *
  * @author Kai S. K. Engelbart
  * @param <T> the type of the Event
  * @since Envoy v0.2-alpha
  */
-public abstract class Event<T> implements IEvent, Serializable {
+public abstract class Event<T> implements Serializable {
 
 	protected final T value;
 
 	private static final long serialVersionUID = 0L;
 
-	protected Event(T value) { this.value = value; }
+	protected Event(T value) {
+		this(value, false);
+	}
+
+	/**
+	 * This constructor is reserved for {@link Valueless} events. No other event should contain null
+	 * values. Only use if really necessary. Using this constructor with {@code true} implies that
+	 * the user has to manually check if the value of the event is null.
+	 */
+	protected Event(T value, boolean canBeNull) {
+		this.value = canBeNull ? value : Objects.requireNonNull(value);
+	}
 
 	/**
 	 * @return the data associated with this event
 	 */
-	public T get() { return value; }
+	public T get() {
+		return value;
+	}
 
 	@Override
-	public String toString() { return String.format("%s[value=%s]", this.getClass().getSimpleName(), value); }
+	public String toString() {
+		return String.format("%s[value=%s]", this.getClass().getSimpleName(), value);
+	}
 
 	/**
 	 * Serves as a super class for events that do not carry a value.
@@ -39,9 +52,13 @@ public abstract class Event<T> implements IEvent, Serializable {
 
 		private static final long serialVersionUID = 0L;
 
-		protected Valueless() { super(null); }
+		protected Valueless() {
+			super(null, true);
+		}
 
 		@Override
-		public String toString() { return this.getClass().getSimpleName(); }
+		public String toString() {
+			return this.getClass().getSimpleName();
+		}
 	}
 }

common/src/main/java/envoy/event/GroupCreation.java

@@ -17,20 +17,19 @@ public final class GroupCreation extends Event<String> {
 	private static final long serialVersionUID = 0L;
 
 	/**
-	 * @param value            the name of this group at creation time
-	 * @param initialMemberIDs the IDs of all {@link User}s that should be group
-	 *                         members from the beginning on (excluding the creator
-	 *                         of this group)
+	 * @param name             the name of this group at creation time
+	 * @param initialMemberIDs the IDs of all {@link User}s that should be group members from the
+	 *                         beginning on (excluding the creator of this group)
 	 * @since Envoy Common v0.1-beta
 	 */
-	public GroupCreation(String value, Set<Long> initialMemberIDs) {
-		super(value);
+	public GroupCreation(String name, Set<Long> initialMemberIDs) {
+		super(name);
 		this.initialMemberIDs = initialMemberIDs != null ? initialMemberIDs : new HashSet<>();
 	}
 
 	/**
-	 * @return the IDs of all {@link User}s that are members from the beginning
-	 *         (excluding the creator of this group)
+	 * @return the IDs of all {@link User}s that are members from the beginning (excluding the
+	 *         creator of this group)
 	 * @since Envoy Common v0.1-beta
 	 */
 	public Set<Long> getInitialMemberIDs() { return initialMemberIDs; }