In this case, we make a RadPane float. Then we move the pane over a compass and drop it. This will execute the closing animation. While the pane is closing, we click and hold again to move the pane while the animation is executing. This will lead to an exception. Here is the stack trace:

   at System.Windows.PresentationSource.CriticalFromVisual(DependencyObject v, Boolean enable2DTo3DTransition) in System.Windows\PresentationSource.cs:line 387
   at Telerik.Windows.Controls.InternalWindow.Standard.DpiHelper.GetPerMonitorDPIAwareScaleFactor(Visual visual)
   at Telerik.Windows.Controls.RadDocking.ScaleGlobalMousePositionIfNeeded(Visual dropTarget, RadSplitContainer container, Point globalMousePos)
   at Telerik.Windows.Controls.RadDocking.GetGroupAtScreenCoordinates(RadDocking docking, Point globalMousePosition, RadSplitContainer rootContainer)
   at Telerik.Windows.Controls.RadDocking.OnDragContainer(RadSplitContainer container, Point globalMousePosition)
   at Telerik.Windows.Controls.Docking.ToolWindow.OnDragDelta(Point globalMousePosition, Rect initialRect, Rect destinationRect, Boolean isResize)
   at Telerik.Windows.Controls.WindowBase.Telerik.Windows.Controls.InternalWindow.IDragAware.OnDragDelta(Point globalMousePosition, Rect initialRect, Rect destinationRect, Boolean isResize)
   at Telerik.Windows.Controls.InternalWindow.WindowHostBase.OnDragDelta(Point globalMousePosition, Rect initialRect, Rect destinationRect, Boolean isResize)
   at Telerik.Windows.Controls.InternalWindow.ChromelessWindowHelper.CoerceWindowRect(IntPtr lParam)
   at Telerik.Windows.Controls.InternalWindow.ChromelessWindowHelper.HandleMoving(IntPtr hwnd, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at Telerik.Windows.Controls.InternalWindow.ChromelessWindowHelper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at System.Windows.Interop.HwndSource.PublicHooksFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) in System.Windows.Interop\HwndSource.cs:line 1312
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)