/// <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);
}