//鼠標是否拖動標志
        private bool isDragging = false;
        //鼠標按下時的位置
        private Point downPosition;
        //鼠標按下時的窗體位置
        private Point lastFormPosition;
        
        /// <summary>
        /// 鼠標按下事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void label_MouseDown(object sender, MouseEventArgs e)
        {
            //判斷是否為鼠標左鍵按下
            if (e.Button == MouseButtons.Left)
            {
                //置標志為true
                isDragging = true;
                //保存當前鼠標坐標
                downPosition = Cursor.Position;
                //保存當前窗體坐標
                lastFormPosition = this.Location;
            }
        }
        /// <summary>
        ///  鼠標移動事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void label_MouseMove(object sender, MouseEventArgs e)
        {
            //判斷鼠標左鍵是否按下
            if (isDragging)
            {
                // 計算鼠標移動的偏移量
                int moveX = Cursor.Position.X - downPosition.X;
                int moveY = Cursor.Position.Y - downPosition.Y;

                // 更新窗體的位置
                this.Location = new Point(lastFormPosition.X + moveX, lastFormPosition.Y + moveY);
            } 
        }
        /// <summary>
        /// 鼠標松開事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void label_MouseUp(object sender, MouseEventArgs e)
        {
            //如果是鼠標左鍵松開，則修改標志為false
            if (e.Button == MouseButtons.Left)
            {
                isDragging = false;
            }
        }

   private const int HT_CAPTION = 0x2;//窗體標題
   private const int WM_NCLBUTTONDOWN = 0xA1;//鼠標點擊的是非客戶區(qū)

   [DllImport("user32.dll")]
   public static extern bool ReleaseCapture();
   [DllImport("user32.dll")]
   public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);

   /// <summary>
   /// 窗體鼠標移動事件
   /// </summary>
   /// <param name="sender"></param>
   /// <param name="e"></param>
   private void test1_MouseMove(object sender, MouseEventArgs e)
   {
       if (e.Button == MouseButtons.Left)
       {
           //釋放鼠標捕獲
           ReleaseCapture();
           //非客戶區(qū)鼠標的拖動窗體消息
           SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
       } 
   }

 internal static int WM_NCHITTEST = 0x84;
 internal static IntPtr HTCLIENT = (IntPtr)0x1;
 internal static IntPtr HTCAPTION = (IntPtr)0x2;
 internal static int WM_NCLBUTTONDBLCLK = 0x00A3;
 protected override void WndProc(ref Message m)
 {
     if (m.Msg == WM_NCLBUTTONDBLCLK)
     {
         return;
     }
     if (m.Msg == WM_NCHITTEST)
     {
         base.WndProc(ref m);
         if (m.Result == HTCLIENT)
         {
             m.HWnd = this.Handle;
             m.Result = HTCAPTION;
         }
         return;
     }
     base.WndProc(ref m);
 }