internal static extern bool UpdateLayeredWindow(IntPtr hwnd, IntPtr hdcDst, ref PointStruct pptDst, ref SizeStruct psize, IntPtr hdcSrc, ref PointStruct pprSrc, int crKey, ref Blendfunction pblend, int dwFlags);
internal static extern bool ScreenToClient(IntPtr hWnd, ref PointStruct pt);
internal static extern bool ClientToScreen(IntPtr hWnd, ref PointStruct pt);