NullReferenceException

Hi,

If you double click with the right mouse button on a "ToolWindowContainerTab" very rapidly, you can produce a NullReferenceException.
You can reproduce it with the docking demo in the sample browser.
It is not easy to reproduce, because you have to move the mouse while clicking.
Otherwise the context menu is shown.

System.NullReferenceException: object reference not set to an instance of an object.
   at ActiproSoftware.UIStudio.TabStrip.TabStripTab.OnMouseUp(MouseEventArgs e)
   at ActiproSoftware.WinUICore.UIElement.#jxe(MouseEventArgs #yhb)
   at ActiproSoftware.WinUICore.UIControl.OnMouseUp(MouseEventArgs e)
   at ActiproSoftware.UIStudio.TabStrip.TabStrip.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

I can reproduce the issue in my application too.
Since the call-stack doesn't contain any of my code, I am wondering if there is a workaround.
A simple try-catch-block at the right place would be sufficient.