public partial class Desktop : Form
    {
        private Point mPoint = new Point();//記錄鼠標指針的坐標 
        private bool isMouseDown = false; //記錄鼠標按鍵是否按下 
        public Desktop()
        {
            InitializeComponent();
            Init();
        }

        public void Init()
        {
            //鼠標按下事件
            this.MouseDown += Desktop_MouseDown;
            //鼠標移動事件
            this.MouseMove += Desktop_MouseMove;
            this.MouseUp += Desktop_MouseUp;
        }

        private void Desktop_MouseUp(object sender, MouseEventArgs e)
        {
            // 修改鼠標狀態(tài)isMouseDown的值 
            // 確保只有鼠標左鍵按下并移動時，才移動窗體 
            if (e.Button == MouseButtons.Left)
            {
                isMouseDown = false;
            }
        }

        private void Desktop_MouseMove(object sender, MouseEventArgs e)
        {
            if (isMouseDown)
            {
                Point myPosittion = MousePosition;
                myPosittion.Offset(-mPoint.X, -mPoint.Y);
                Location = myPosittion;
            }
        }

        private void Desktop_MouseDown(object sender, MouseEventArgs e)
        {

            if (e.Button == MouseButtons.Left)
            {
                mPoint.X = e.X;
                mPoint.Y = e.Y;
                isMouseDown = true;
            }
        }

    }