private Rectangle dragBoxFromMouseDown;
        private int rowIndexFromMouseDown;
        private int rowIndexOfItemUnderMouseToDrop;

        private void stuffDataGridView_MouseMove(object sender, MouseEventArgs e)
        {
            if ((e.Button & MouseButtons.Left) == MouseButtons.Left)
            {
                if (dragBoxFromMouseDown != Rectangle.Empty &&
                  !dragBoxFromMouseDown.Contains(e.X, e.Y))
                {

                    DragDropEffects dropEffect = stuffDataGridView.DoDragDrop(
                    stuffDataGridView.Rows[rowIndexFromMouseDown],
                    DragDropEffects.Move);
                }
            }
        }





        private void stuffDataGridView_MouseDown(object sender, MouseEventArgs e)
        {
            rowIndexFromMouseDown = stuffDataGridView.HitTest(e.X, e.Y).RowIndex;

            if (rowIndexFromMouseDown != -1)
            {

                Size dragSize = SystemInformation.DragSize;

                dragBoxFromMouseDown = new Rectangle(new Point(e.X - (dragSize.Width / 2),
                                        e.Y - (dragSize.Height / 2)),
                          dragSize);
            }
            else
                dragBoxFromMouseDown = Rectangle.Empty;
        }







        private void departmentDataGridView_DragDrop(object sender, DragEventArgs e)
        {
            Point clientPoint = departmentDataGridView.PointToClient(new Point(e.X, e.Y));

            rowIndexOfItemUnderMouseToDrop =
              departmentDataGridView.HitTest(clientPoint.X, clientPoint.Y).RowIndex;

            if (e.Effect == DragDropEffects.Move)
            {
                DataGridViewRow rowToMove = e.Data.GetData(
                  typeof(DataGridViewRow)) as DataGridViewRow;
                ouputDataGridView.Rows.Insert(rowIndexOfItemUnderMouseToDrop, rowToMove);

            }
        }