Implemented notification of user if he can no longer send messages

This only occurs when he is in offline mode and runs out of messageIDs
to use.
Additionally implemented:
- automatically disabled user of posting after that condition is reached
- an infoLabel used to commjunicate some events with the user
- (in parts) a new UI design

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

@@ -16,6 +16,7 @@ import javafx.scene.image.ImageView;
 import javafx.scene.input.KeyCode;
 import javafx.scene.input.KeyEvent;
 import javafx.scene.paint.Color;
+import javafx.scene.paint.Paint;
 
 import envoy.client.data.Chat;
 import envoy.client.data.LocalDB;
@@ -62,6 +63,9 @@ public final class ChatScene {
 	@FXML
 	private Label remainingChars;
 
+	@FXML
+	private Label infoLabel;
+
 	@FXML
 	private MenuItem deleteContactMenuItem;
 
@@ -70,6 +74,8 @@ public final class ChatScene {
 	private WriteProxy		writeProxy;
 	private SceneContext	sceneContext;
 
+	private boolean postingPermanentlyDisabled = false;
+
 	private Chat currentChat;
 
 	private static final Settings	settings			= Settings.getInstance();
@@ -165,6 +171,7 @@ public final class ChatScene {
 		userList.setItems(FXCollections.observableList(localDB.getChats().stream().map(Chat::getRecipient).collect(Collectors.toList())));
 		contactLabel.setText(localDB.getUser().getName());
 		MessageListCell.setUser(localDB.getUser());
+		if (!client.isOnline()) updateInfoLabel("You are offline", Color.YELLOW);
 	}
 
 	/**
@@ -244,10 +251,15 @@ public final class ChatScene {
 	 */
 	@FXML
 	private void checkPostConditions(KeyEvent e) {
-		if (!postButton.isDisabled() && (settings.isEnterToSend() && e.getCode() == KeyCode.ENTER
-				|| !settings.isEnterToSend() && e.getCode() == KeyCode.ENTER && e.isControlDown()))
-			postMessage();
-		postButton.setDisable(messageTextArea.getText().isBlank() || currentChat == null);
+		if (!postingPermanentlyDisabled) {
+			if (!postButton.isDisabled() && (settings.isEnterToSend() && e.getCode() == KeyCode.ENTER
+					|| !settings.isEnterToSend() && e.getCode() == KeyCode.ENTER && e.isControlDown()))
+				postMessage();
+			postButton.setDisable(messageTextArea.getText().isBlank() || currentChat == null);
+		} else if (!infoLabel.getText().equals("You need to go online to send more messages"))
+			// Informing the user that he is a f*cking moron and should use Envoy online
+			// because he ran out of messageIDs to use
+			updateInfoLabel("You need to go online to send more messages", Color.RED);
 	}
 
 	/**
@@ -286,6 +298,12 @@ public final class ChatScene {
 	 */
 	@FXML
 	private void postMessage() {
+		postingPermanentlyDisabled = !(client.isOnline() || localDB.getIDGenerator().hasNext());
+		if (postingPermanentlyDisabled) {
+			postButton.setDisable(true);
+			updateInfoLabel("You need to go online to send more messages", Color.RED);
+			return;
+		}
 		final var text = messageTextArea.getText().strip();
 		if (text.isBlank()) throw new IllegalArgumentException("A message without visible text can not be sent.");
 		try {
@@ -322,6 +340,19 @@ public final class ChatScene {
 	 */
 	private void scrollToMessageListEnd() { messageList.scrollTo(messageList.getItems().size() - 1); }
 
+	/**
+	 * Updates the {@code infoLabel}.
+	 *
+	 * @param text     the text to use
+	 * @param textfill the color in which to display information
+	 * @since Envoy Client v0.1-beta
+	 */
+	private void updateInfoLabel(String text, Paint textfill) {
+		infoLabel.setText(text);
+		infoLabel.setTextFill(textfill);
+		infoLabel.setVisible(true);
+	}
+
 	// Context menu actions
 
 	@FXML

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

@@ -115,8 +115,7 @@ public final class LoginScene {
 		if (registerCheckBox.isSelected() && !passwordField.getText().equals(repeatPasswordField.getText())) {
 			new Alert(AlertType.ERROR, "The entered password is unequal to the repeated one").showAndWait();
 			repeatPasswordField.clear();
-		}
-		else performHandshake(
+		} else performHandshake(
 				new LoginCredentials(userTextField.getText(), passwordField.getText().toCharArray(), registerCheckBox.isSelected(), Startup.VERSION));
 	}
 
@@ -190,9 +189,8 @@ public final class LoginScene {
 
 		localDB.synchronize();
 
-		if (client.isOnline()) {
-			writeProxy.flushCache();
-		} else
+		if (client.isOnline()) writeProxy.flushCache();
+		else
 			// Set all contacts to offline mode
 			localDB.getChats()
 				.stream()