* 首先将窗体的边框样式修改为None，让窗体没有标题栏
         * 实现这个效果使用了三个事件：鼠标按下、鼠标弹起、鼠标移动
         * 鼠标按下时更改变量isMouseDown标记窗体可以随鼠标的移动而移动
         * 鼠标移动时根据鼠标的移动量更改窗体的location属性，实现窗体移动
         * 鼠标弹起时更改变量isMouseDown标记窗体不可以随鼠标的移动而移动
         */
        private bool isMouseDown = false;
        private Point FormLocation;     //form的location
        private Point mouseOffset;      //鼠标的按下位置
        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                isMouseDown = true;
                FormLocation = this.Location;
                mouseOffset = Control.MousePosition;
            }
        }

        private void Form1_MouseUp(object sender, MouseEventArgs e)
        {
            isMouseDown = false;
        }

        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            int _x = 0;
            int _y = 0;
            if (isMouseDown)
            {
                Point pt = Control.MousePosition;
                _x = mouseOffset.X - pt.X;
                _y = mouseOffset.Y - pt.Y;

                this.Location = new Point(FormLocation.X - _x, FormLocation.Y - _y);
            }

        }