public static extern CombineRgnResult CombineRgn(IntPtr hrgnDest, IntPtr hrgnSrc1, IntPtr hrgnSrc2, RGN fnCombineMode);
public static extern RegionType CombineRgn(HRGN hrgnDst, HRGN hrgnSrc1, HRGN hrgnSrc2, RGN iMode);
public static partial RegionType CombineRgn(HRGN hrgnDst, HRGN hrgnSrc1, HRGN hrgnSrc2, RGN iMode);