Fixed threading bug

window/ChatWindow.java

@@ -1,6 +1,7 @@
 package window;
 
 import javafx.application.Application;
+import javafx.application.Platform;
 import javafx.event.EventHandler;
 import javafx.geometry.Insets;
 import javafx.scene.Scene;
@@ -87,15 +88,18 @@ public class ChatWindow extends Application {
         }
     }
 
-    public void addMessage(String user, String message) { addMessage(user, message, true); }
+    public void addMessage(String user, String message) { Platform.runLater(() -> addMessage(user, message, true)); }
 
     public void addMessage(String user, String message, boolean doTimestamp) {
-        String timestamp = doTimestamp ? (new Date()).toString() : "";
-        Label messageLabel = new Label();
-        messageLabel.textProperty().setValue(messageLabel.textProperty().getValue() + timestamp + ": [" + user + "] " + message);
-        messageLabel.setWrapText(true);
-        messageLabel.prefWidthProperty().bind(messagePane.prefWidthProperty());
-        messagePane.getChildren().add(messageLabel);
+        Platform.runLater(() ->
+        {
+            String timestamp = doTimestamp ? (new Date()).toString() : "";
+            Label messageLabel = new Label();
+            messageLabel.textProperty().setValue(messageLabel.textProperty().getValue() + timestamp + ": [" + user + "] " + message);
+            messageLabel.setWrapText(true);
+            messageLabel.prefWidthProperty().bind(messagePane.prefWidthProperty());
+            messagePane.getChildren().add(messageLabel);
+        });
     }
 
     @Override