BOOL RedrawWindow( LPCRECT lpRectUpdate = NULL, HRGN hRgnUpdate = NULL, UINT flags = RDW_INVALIDATE | RDW_UPDATENOW | RDW_ERASE );
See RedrawWindow in the Win32 SDK.
Remarks
Updates a specified rectangle or region in the client area.
CWindow Overview | Class Members
See Also CWindow::UpdateWindow, RECT