Occasional NullPointerException from ScrollBar when using touchscreen.

The exception is following:
java.lang.NullPointerException
at com.sun.javafx.scene.control.skin.ScrollBarSkin$8.handle(ScrollBarSkin.java:217)
at com.sun.javafx.scene.control.skin.ScrollBarSkin$8.handle(ScrollBarSkin.java:201)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:113)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.scene.control.skin.ScrollPaneSkin$13.dispatchEvent(ScrollPaneSkin.java:462)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:113)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:113)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:113)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:113)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:202)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3388)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3227)
at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3179)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1580)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2325)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:287)
at com.sun.glass.ui.View.handleMouseEvent(Unknown Source)
at com.sun.glass.ui.View.notifyMouse(Unknown Source)
at com.sun.glass.ui.lens.LensView._notifyMouse(Unknown Source)
at com.sun.glass.ui.lens.LensTouchInputSupport.notifyMouseEvent(Unknown Source)
at com.sun.glass.ui.lens.LensTouchInputSupport.processTouchEvents(Unknown Source)
at com.sun.glass.ui.lens.LensApplication$LensTouchEvent.dispatch(Unknown Source)
at com.sun.glass.ui.lens.LensApplication._runLoop(Unknown Source)
at com.sun.glass.ui.lens.LensApplication.access$400(Unknown Source)
at com.sun.glass.ui.lens.LensApplication$4.run(Unknown Source)
at java.lang.Thread.run(Thread.java:722)