When scrolling horizontal the following exception occured (this was not reproducible):

java.lang.NullPointerException
 at com.sun.javafx.scene.control.skin.ScrollBarSkin$8.handle(ScrollBarSkin.java:215)
 at com.sun.javafx.scene.control.skin.ScrollBarSkin$8.handle(ScrollBarSkin.java:199)
 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.scene.control.skin.ScrollPaneSkin$11.dispatchEvent(ScrollPaneSkin.java:440)
 at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
 at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
 at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
 at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
 at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
 at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
 at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
 at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
 at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
 at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
 at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
 at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
 at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
 at javafx.event.Event.fireEvent(Event.java:171)
 at javafx.scene.Scene$MouseHandler.process(Scene.java:3324)
 at javafx.scene.Scene$MouseHandler.process(Scene.java:3164)
 at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3119)
 at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1559)
 at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2261)
 at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:228)
 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$3$1.run(WinApplication.java:73)
 at java.lang.Thread.run(Thread.java:722)