private Point mPoint = new Point();

         private void 选择控件_MouseDown(object sender, MouseEventArgs e)

         {

             mPoint.X = e.X;

             mPoint.Y = e.Y;

         }

         private void 选择控件_MouseMove(object sender, MouseEventArgs e)

         {

             if (e.Button == MouseButtons.Left)

             {

                 Point myPosittion = MousePosition;

                 myPosittion.Offset(-mPoint.X, -mPoint.Y);

                 Location = myPosittion;

             }

         }