Run the attached app and click on the TextField. You'll get the following NPE:

java.lang.NullPointerException
at javafx.scene.Scene$KeyHandler.setFocusOwner(Scene.java:3085)
at javafx.scene.Scene$KeyHandler.requestFocus(Scene.java:3146)
at javafx.scene.Scene$KeyHandler.access$1900(Scene.java:3069)
at javafx.scene.Scene.requestFocus(Scene.java:1533)
at javafx.scene.Node.requestFocus(Node.java:5484)
at com.sun.javafx.scene.control.behavior.TextFieldBehavior.mousePressed(TextFieldBehavior.java:176)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:335)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:329)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$MouseHandler.process(Scene.java:2897)
at javafx.scene.Scene$MouseHandler.process(Scene.java:2691)
at javafx.scene.Scene$MouseHandler.access$1300(Scene.java:2657)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1281)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:1915)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:215)
at com.sun.glass.ui.View.handleMouseEvent(View.java:493)
at com.sun.glass.ui.View.notifyMouse(View.java:871)
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:722)