Thanks WILL and sorry for the double post ops:

Hi Andreaz, I tried it and it didn't help :cry:

In fact the same happens (Render freezing) even when not using UnDelphiX (i.e. just using and ordinary TForm and and a TBitmap Canvas to draw on. I'm wondering if Windows is suppressing certain Events like OnIdle or OnTimer when dragging a window or pop-up menus are on screen?