Fixed possible name conflict when creating new themes.

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

@@ -5,6 +5,7 @@ import java.awt.event.ActionListener;
 import java.awt.event.ItemEvent;
 import java.awt.event.ItemListener;
 import java.util.Arrays;
+import java.util.Map;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -118,7 +119,10 @@ public class ThemeCustomizationPanel extends SettingsPanel {
 		return (evt) -> {
 			if (themeChanged) {
 				try {
-					String name = JOptionPane.showInputDialog("Enter a name for the new theme");
+					String name = "";
+					while (name == "") {
+						name = newName();
+					}
 					logger.log(Level.FINEST, name);
 					Settings.getInstance().addNewThemeToMap(new Theme(name, temporaryTheme));
 					themeArray							= Arrays.copyOf(themeArray, themeArray.length + 1);
@@ -229,4 +233,16 @@ public class ThemeCustomizationPanel extends SettingsPanel {
 
 		colorsPanel.add(button, gbc_button);
 	}
+	
+	private String newName () {
+		String name = JOptionPane.showInputDialog("Enter a name for the new theme");
+		for (Map.Entry<String, Theme> entry : Settings.getInstance().getThemes().entrySet()) {
+		   System.out.println(entry.getKey().toString());
+			if(entry.getKey().equalsIgnoreCase(name)) {
+		    	JOptionPane.showMessageDialog(getParent(), "Name is already used! Please choose another one.");
+		    	return "";
+		    }
+		}
+		return name;
+	}
 }