The IDirectDrawSurface4::GetFlipStatus method indicates whether the surface has finished its flipping process.
HRESULT GetFlipStatus(
  DWORD dwFlags  
);
 If the method succeeds, the return value is DD_OK.
If the method fails, the return value is DDERR_WASSTILLDRAWING if the surface has not finished its flipping process, or one of the following error values:
| DDERR_INVALIDOBJECT | 
| DDERR_INVALIDPARAMS | 
| DDERR_INVALIDSURFACETYPE | 
| DDERR_SURFACEBUSY | 
| DDERR_SURFACELOST | 
| DDERR_UNSUPPORTED | 
  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.