Run the attached test case. It shows a Swing window with a menu, and a JFXPanel inside it. Click on the menu (it's empty, so no nested menu is opened) and then click on the JFXPanel. The following exception is thrown:

Exception in runnable
java.lang.NullPointerException
    at javafx.scene.Scene$ClickCounter.access$4700(Scene.java:2294)
    at javafx.scene.Scene$ClickGenerator.postProcess(Scene.java:2454)
    at javafx.scene.Scene$ClickGenerator.access$5900(Scene.java:2390)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:2673)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:2489)
    at javafx.scene.Scene$MouseHandler.access$1200(Scene.java:2462)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1195)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:1779)
    at com.sun.javafx.tk.quantum.EmbeddedScene$2.run(EmbeddedScene.java:317)
    at com.sun.javafx.application.PlatformImpl$3.run(PlatformImpl.java:108)
    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$2$1.run(WinApplication.java:62)
    at java.lang.Thread.run(Thread.java:662)