Call this member function to draw the current window in the specified device context, which is most commonly in a printer device context.
CWnd::DefWindowProc function processes this message based on which drawing option is specified:
If PRF_CHECKVISIBLE is specified and the window is not visible, do nothing.
If PRF_NONCLIENT is specified, draw the nonclient area in the given device context.
If PRF_ERASEBKGND is specified, send the window a WM_ERASEBKGND message.
If PRF_CLIENT is specified, send the window a WM_PRINTCLIENT message.
If PRF_CHILDREN is set, send each visible child window a WM_PRINT message.
If PRF_OWNED is set, send each visible owned window a WM_PRINT message.