最早这是思想实现与MacOS X系统上，被称之为FaceTop。

[DllImport("user32.dll", SetLastError=true)]
        static extern int GetWindowLong(IntPtr hWnd, int nIndex);
        [DllImport("user32.dll", SetLastError=true)]
        static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

        private const int  GWL_EXSTYLE = -20;
        private const int  WS_EX_TRANSPARENT = 0x20;

        private void VideoPlayer_Load(object sender, System.EventArgs e)
        {
            // Add WS_EX_TRANSPARENT style so that mouse, keyboard etc. events pass

            // thru us.

            int exstyle = GetWindowLong(this.Handle, GWL_EXSTYLE);
            exstyle |= WS_EX_TRANSPARENT;
            SetWindowLong(this.Handle, GWL_EXSTYLE, exstyle);
        }