/// <summary>
        /// 设置窗体的圆角矩形
        /// </summary>
        /// <param name="form">需要设置的窗体</param>
        /// <param name="rgn_radius">圆角矩形的半径</param>
        public static void setRoundRectRgn(this Form form, int rgn_radius)
        {
            int hRgn = 0;

            hRgn = WindowsUtil.CreateRoundRectRgn(0, 0, form.Width, form.Height, rgn_radius, rgn_radius);
            WindowsUtil.SetWindowRgn(form.Handle, hRgn, true);
            WindowsUtil.DeleteObject(hRgn);
        }