What is the difference between GetClientRect and GetWindowRect in WinApi?

Question

What of these should I use in InvalidateRect to refresh my window? And why?

Answer 1

A very simple explanation is that GetWindowRect() gives you the rectangle that includes the borders of the window. GetClientRect() gives you the rectangle that excludes the borders - the area that is allocated to the window specific drawing.

Please note that GetWindowRect() returns a rectangle in screen coordinates - coordinates that are relative to the screen/monitor. GetClientRect() returns a rectangle that is relative to itself.