DWORD (*PDD_SURFCB_FLIP)(
PDD_FLIPDATA lpFlip
);
Flip causes the surface memory associated with the target surface to become the primary surface, and the current surface to become the nonprimary surface.
Flip returns a DDHAL_DRIVER_Xxx callback code that indicates how the driver handled the call. These return codes are defined in ddrawint.h.
Flip allows a display driver to perform multi-buffering.