Transparent non-client area

Question

I am creating a TextBox control subclass using Windows Forms. I am using the WM_NCCALCSIZE to change the client area (to enlarge the non-client area) but I have not found any solution on how to make the non-client area transparent. Is there any simple way to paint to non-client area in WM_NCPAINT in transparent way to duplicate the underlying window's background in intersecting region of the child control?

Answer 1

UpdateLayeredWindow is what you need.

http://msdn.microsoft.com/en-us/library/windows/desktop/ms633556%28v=vs.85%29.aspx http://msdn.microsoft.com/en-us/library/ms997507.aspx