private void FormSample_Load(object sender, EventArgs e)         {             //注册事件             this.MouseWheel += new MouseEventHandler(FormSample_MouseWheel);         }         /// <summary>         /// 滚动方法         /// </summary>         /// <param name="sender"></param>         /// <param name="e"></param>         void FormSample_MouseWheel(object sender, MouseEventArgs e)         {             //获取光标位置             Point mousePoint = new Point(e.X,e.Y);             //换算成相对本窗体的位置             mousePoint.Offset(this.Location.X, this.Location.Y);                   //判断是否在panel内             if (pnlDownload.RectangleToScreen(               pnlDownload.DisplayRectangle).Contains(mousePoint))             {                 //滚动                 pnlDownload.AutoScrollPosition = new Point( , pnlDownload.VerticalScroll.Value - e.Delta);             }         }