C# winform 窗体最大化及还原方法

假设是单击button触发的click事件：

        /// <summary>
        /// 全屏按钮的Click事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnFullScreen_Click(object sender, EventArgs e)
        {
            if (this.WindowState == FormWindowState.Maximized)
            {
                this.WindowState = FormWindowState.Normal;
                this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.Sizable;
            }
            else
            {
                this.FormBorderStyle = FormBorderStyle.None;
                this.WindowState = FormWindowState.Maximized;
            }
        }