WM_NCPAINT

This message is sent to a window when its frame needs painting.

Parameters

wParam

This parameter contains the update region of the window, clipped to the window frame.

lParam

This parameter is not used.

Comments

The DefWindowProc function paints the window frame.

An application can intercept this message and paint its own custom window frame. Remember that the clipping region for a window is always rectangular, even if the shape of the frame is altered.