In the call back procedures that VB takes care of you it accesses it's hWnd of the thing that called it, quite complicated really (if you think about it too hard!) but a bit simple at the same time...

Anyways, you need to fix the problem in your cursor, how that it takes the DC but it doesnt refresh, so that I had a winzip open, it's titlebar was green. I clicked elsewhere and the titlebar turned gray (that's the colour scheme for my computer ) and when I put the mouse over it, the titlebar showed through green.

Ah, "Also: when loading my app, I grap a copy of the desktop, but when the desktop changes (like some selection with the mouse), the memory DC does not change! Any suggestions?"

I see you've already spotted this problem .