When calling Platform.exit() from a MenuItem, JavaFX 2.0 (b30) issues the following error :
java.lang.IllegalStateException: Not on FX application thread; currentThread = JavaFX Application Thread
at com.sun.javafx.tk.Toolkit.checkFxUserThread(Toolkit.java:189)
at com.sun.javafx.tk.quantum.QuantumToolkit.checkFxUserThread(QuantumToolkit.java:321)
at javafx.scene.Scene$MouseHandler.process(Scene.java:1942)
at javafx.scene.Scene$MouseHandler.process(Scene.java:1931)
at javafx.scene.Scene$MouseHandler.access$1000(Scene.java:1904)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1005)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:1551)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:154)
at com.sun.glass.ui.View.handleMouseEvent(View.java:257)
at com.sun.glass.ui.View.notifyMouse(View.java:514)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$1$1.run(WinApplication.java:49)
at java.lang.Thread.run(Thread.java:722)
Exception in thread "JavaFX Application Thread"


This exception should not be thrown as we are in the JavaFX Application Thread.
The application still exits after the exception is thrown.

Sample code:

public class Main extends Application {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Application.launch(Main.class, args);
    }

    @Override
    public void start(Stage primaryStage) {
        // Construct GUI.
        MenuItem exitItem = new MenuItemBuilder().id("exitItem").text("Exit").build();
        exitItem.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent event) {
                exit(0);
            }
        });
        Menu fileMenu = new MenuBuilder().id("fileMenu").text("File").build();
        fileMenu.getItems().addAll(exitItem);
        Menu editMenu = new MenuBuilder().id("editMenu").text("Edit").build();
        Menu viewMenu = new MenuBuilder().id("viewMenu").text("View").build();
        Menu helpMenu = new MenuBuilder().id("helpMenu").text("Help").build();
        MenuBar menuBar = new MenuBarBuilder().id("menuBar").build();
        menuBar.getMenus().addAll(fileMenu, editMenu, viewMenu, helpMenu);
        ////////////////////////////////////////////////////////////
        primaryStage.setTitle("Hello World");
        BorderPane root = new BorderPane();
        root.setTop(menuBar);
        Scene scene = new Scene(root, 300, 250, Color.LIGHTGREEN);
        primaryStage.setScene(scene);
        primaryStage.setVisible(true);
    }
    
    public void exit(int errorCode) {
        Platform.exit();
    }
}