Winform圆角窗体，timer倒计时关闭窗体

public partial class mymessagebox : form
{
        // 自动关闭的时间限制，如3为3秒后自动关闭
        private int _second;

        public int second
        {
            get { return _second; }
            set { _second = value; }
        }
        // 计数器，用以判断当前窗口弹出后持续的时间
        private int counter;
        public mymessagebox(string message)
        {
            initializecomponent();
            this._second = second;
            // 初始化计数器
            this.counter = 0;
            this.label1.text = message;
            this.buttonex1.text = string.format("确定({0})", this._second - this.counter);
            // 激活并启动timer，设置timer的触发间隔为1000毫秒（1秒）
            this.timer1.enabled = true;
            this.timer1.interval = 1000;
            this.timer1.start();
        }

        private void buttonex1_click(object sender, eventargs e)
        {
            this.close();
        }

        private void timer1_tick(object sender, eventargs e)
        {
            if (this.counter < this._second)
            {
                // 刷新按钮的文本
                this.buttonex1.text = string.format("确定({0})", this._second - this.counter - 1);
                this.refresh();
                // 计数器自增
                this.counter++;
            }
            // 如果到达时间限制
            else
            {
                // 关闭timer
                this.timer1.enabled = false;
                this.timer1.stop();
                // 关闭对话框
                this.close();
            }
        }

        // "画圆角"
        public void setwindowregion()
        {
            system.drawing.drawing2d.graphicspath formpath;
            formpath = new system.drawing.drawing2d.graphicspath();
            rectangle rect = new rectangle(0, 0, this.width, this.height);
            formpath = getroundedrectpath(rect, 10);
            this.region = new region(formpath);
        }

        /// 
        /// 
        /// 
        ///窗体大小
        ///圆角大小
        /// 
        private graphicspath getroundedrectpath(rectangle rect, int radius)
        {
            int diameter = radius;
            rectangle arcrect = new rectangle(rect.location, new size(diameter, diameter));
            graphicspath path = new graphicspath();

            path.addarc(arcrect, 180, 90);//左上角

            arcrect.x = rect.right - diameter;//右上角
            path.addarc(arcrect, 270, 90);

            arcrect.y = rect.bottom - diameter;// 右下角
            path.addarc(arcrect, 0, 90);

            arcrect.x = rect.left;// 左下角
            path.addarc(arcrect, 90, 90);
            path.closefigure();
            return path;
        }
        private void mymessagebox_resize(object sender, eventargs e)
        {
            if (this.windowstate == formwindowstate.normal)
            {
                setwindowregion();
            }
            else
            {
                this.region = null;
            }
        }
}