NullReferenceException: 未将对象引用设置到对象的实例。
StackTrace:
   在 MS.Internal.PointUtil.TryClientToRoot(Point point, PresentationSource presentationSource, Boolean throwOnError, Boolean& success)
   在 System.Windows.Input.StylusWisp.WispStylusDevice.GetPosition(IInputElement relativeTo)
   在 System.Windows.Input.StylusWisp.WispStylusDevice.ChangeStylusOver(IInputElement stylusOver)
   在 System.Windows.Input.StylusWisp.WispLogic.SelectStylusDevice(WispStylusDevice wispStylusDevice, IInputElement newOver, Boolean updateOver)
   在 System.Windows.Input.WispTabletDevice.DisposeOrDeferDisposal()
   在 System.Windows.Input.StylusWisp.WispTabletDeviceCollection.DisposeTablets()
   在 System.Windows.Input.StylusWisp.WispLogic.OnDispatcherShutdown(Object sender, EventArgs e)
   在 System.EventHandler.Invoke(Object sender, EventArgs e)
   在 System.Windows.Threading.Dispatcher.ShutdownImplInSecurityContext(Object state)
   在 MS.Internal.CulturePreservingExecutionContext.CallbackWrapper(Object obj)
   在 System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   在 MS.Internal.CulturePreservingExecutionContext.Run(CulturePreservingExecutionContext executionContext, ContextCallback callback, Object state)
   在 System.Windows.Threading.Dispatcher.ShutdownImpl()
   在 System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   在 System.Windows.Application.RunDispatcher(Object ignore)
   在 System.Windows.Application.RunInternal(Window window)
   在 Quicker.App.Main()