I created a Windows Forms project that references UrhoSharp and paints into a Panel of the main Window. The window and Urho both run on the main thread. I derived a class from Urho.Application and from it's OnUpdate override I update a control in the Window and call Invalidate on it. As long as I don't move the mouse the Control is painted smoothly, but as soon as I move the mouse, the Paint-Event is sent only occasionally. Even without the custom painting and without Invalidate, the main window background gets black as soon as Urho.Application.Run is called.