public static extern int UpdateLayeredWindow(IntPtr hWnd,
IntPtr hdcDst,
ref POINT pptDst,
ref SIZE psize,
IntPtr hdcSrc,
ref POINT pptSrc,
uint crKey,
ref BLENDFUNCTION pblend,
uint dwFlags);
public static extern bool AlphaBlend([In] SafeHandle hdcDest,
int nXOriginDest, int nYOriginDest,
int nWidthDest, int nHeightDest,
[In] SafeHandle hdcSrc,
int nXOriginSrc, int nYOriginSrc, int nWidthSrc, int nHeightSrc,
BLENDFUNCTION blendFunction);