From the MSDN documentation:
The BeginPaint function validates the entire client area.
The ValidateRect function should not be called if a portion of the
update region must be validated before the next WM_PAINT message is
generated.1
I've been programming with Win32 API for years, and I've never thought to call the ValidateRect function. A co-worker of mine today pointed that we were missing a call to ValidateRect, which fixed a bug we were having doing some high-speed animation using GDI (I know, an oxymoron)
Can someone tell me whether or not a call to ValidateRect is neccessary after a BeginPaint/EndPaint pair? I have seen no documentation at MSDN that sheds light on this, and what documentation and examples I do see that you do not need to.