The IDirectDrawSurface4::AddOverlayDirtyRect method is not currently implemented.
HRESULT AddOverlayDirtyRect(
LPRECT lpRect
);
Windows NT/2000: Requires Windows 2000.
Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
Header: Declared in ddraw.h.
Import Library: Use ddraw.lib.