protected override CreateParams CreateParams
        {
            get
            {
                const int WS_EX_APPWINDOW = 0x40000;
                const int WS_EX_TOOLWINDOW = 0x80;
                CreateParams cp = base.CreateParams;
                cp.ExStyle &= (~WS_EX_APPWINDOW);    // 不显示在TaskBar
                cp.ExStyle |= WS_EX_TOOLWINDOW;      // 不显示在Alt+Tab
                return cp;
            }
        }