I need control( for example button) to draw itself on memory device context.
I created this device context and call ::SendMessage(hwndControl, WM_PAINT,
(WPARAM)memDC.GetSafeHdc(), 0). The problem is that in this case invalid
rectangle is empty and control doesn't paint itself. If I specify
InvalidateRect(NULL) before sending message then control does paint itself
on memory DC but it also paints itself on window DC. I also tried to call
ValidateRect(NULL) just after sending message but it doesn't help. How can I
force control to draw itself on memory DC only?