I got the following exception every time when I added a MenuBar into an AnchorPane which was already in the scene, but our Scene Build seems continue working.

Glass detected outstanding Java exception at -[GlassViewDelegate sendJavaMouseEvent:]:src/com/sun/mat/ui/GlassViewDelegate.m:476
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at com.sun.javafx.scene.control.skin.MenuBarSkin$17.handle(MenuBarSkin.java:551)
at com.sun.javafx.scene.control.skin.MenuBarSkin$17.handle(MenuBarSkin.java:548)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$MouseHandler.handleEnterExit(Scene.java:2769)
at javafx.scene.Scene$MouseHandler.process(Scene.java:2933)
at javafx.scene.Scene$MouseHandler.process(Scene.java:2689)
at javafx.scene.Scene$MouseHandler.access$1300(Scene.java:2655)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1281)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:1913)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:212)
at com.sun.glass.ui.View.handleMouseEvent(View.java:491)
at com.sun.glass.ui.View.notifyMouse(View.java:869)