I get sometimes the following assertion with these steps :
- Start the tool
- View the CSS Analyzer
- Drop a Button
- From the Properties, change the Alignment property

java.lang.RuntimeException: java.lang.AssertionError
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:251)
at com.sun.glass.ui.View.handleMouseEvent(View.java:528)
at com.sun.glass.ui.View.notifyMouse(View.java:922)
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:67)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.AssertionError
at com.oracle.javafx.authoring.stage.v2.EditModeController.handleMouseEvent(EditModeController.java:178)
at com.oracle.javafx.authoring.stage.v2.EditModeController$1.handle(EditModeController.java:126)
at com.oracle.javafx.authoring.stage.v2.EditModeController$1.handle(EditModeController.java:123)
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)