使用JavaFX控件时“JavaFX应用程序线程”中出现异常

我正在初始化一个带有枚举值的通用JavaFX 8组合框，如下所示：

ObservableList<MyEnumClass> myValues = FXCollections
        .observableArrayList(MyEnumClass.FIRST_ENUM, 
                MyEnumClass.SECOND_ENUM, MyEnumClass.THIRD_ENUM);
myEnumComboBox = new ComboBox<MyEnumClass>(myValues);     

一个测试应用程序按照预期显示带有枚举值的组合框，并且选择其他值也可以正常工作。但有一件事让我困惑：尽管我无法观察到任何明显的故障，但每当我从组合框的菜单中选择新值时，我的Eclipse控制台都会通知我线程JavaFX应用程序线程中出现异常。异常似乎与隐藏组合框弹出控件的本机JavaFX代码有关：

Exception in thread "JavaFX Application Thread" java.lang.IllegalArgumentException: null source
    at java.util.EventObject.<init>(Unknown Source)
    at java.awt.AWTEvent.<init>(Unknown Source)
    at sun.awt.UngrabEvent.<init>(Unknown Source)
    at javafx.embed.swing.SwingNode$10.handle(Unknown Source)
        [9 lines omitted]
    at com.sun.javafx.event.EventUtil.fireEvent(Unknown Source)
    at javafx.event.Event.fireEvent(Unknown Source)
    at com.sun.javafx.stage.WindowPeerListener.focusUngrab(Unknown Source)
        [4 lines omitted]
    at com.sun.glass.ui.Window.handleWindowEvent(Unknown Source)
    at com.sun.glass.ui.Window.notifyFocusUngrab(Unknown Source)
    at com.sun.glass.ui.win.WinWindow._ungrabFocus(Native Method)
    at com.sun.glass.ui.Window.ungrabFocus(Unknown Source)
    at com.sun.javafx.tk.quantum.WindowStage.ungrabFocus(Unknown Source)
    at javafx.stage.Window.decreaseFocusGrabCounter(Unknown Source)
    at javafx.stage.PopupWindow.handleAutohideActivation(Unknown Source)
    at javafx.stage.PopupWindow.impl_visibleChanged(Unknown Source)
    at javafx.stage.Window$9.invalidated(Unknown Source)
    at javafx.beans.property.BooleanPropertyBase.markInvalid(Unknown Source)
    at javafx.beans.property.BooleanPropertyBase.set(Unknown Source)
    at javafx.stage.Window.setShowing(Unknown Source)
    at javafx.stage.Window.hide(Unknown Source)
    at javafx.stage.PopupWindow.hide(Unknown Source)
    at com.sun.javafx.scene.control.skin.ComboBoxPopupControl.hide(Unknown Source)
        [44 lines omitted]
    at java.lang.Thread.run(Unknown Source)

有人能解释一下这里到底发生了什么，我能或应该做些什么吗

---

编辑-该异常是由与组合框在同一窗格上的某个早期实验的遗留物引起的。删除SwingNode使异常消失

很难说，但从JavaFX到Swing的AWT事件系统的事件流似乎是一个问题？你在做什么？你能提供一个既最小又可执行的程序吗？