DND is now working for alienwindows
Revert "ui designer fixes. Now resizing using grips works."

This reverts commit 765f9a75b734662b998fe2aa8ad65647728171f8.

The window dipsatcher now performs a passive grab of the mouse on mouse down on a window. so most of this patch is irrelevant. A better solution for invalidating a parent must
be implemented.
alienwindows: start of InvalidateRect, just an empty shell for now. InvalidateRect is used on the parent if a widget is moved
Implemented InvalidateRect