private void dataGridViewInOut_DragDrop(object sender, DragEventArgs e)
        {
            DataGridViewRow row = e.Data.GetData(typeof(DataGridViewRow)) as DataGridViewRow;
            if (row != null)
            {
                //for debug
                MessageBox.Show(row.Cells[1].Value.ToString());
               //не работает
                dataGridViewInOut.CurrentCell.Value = row.Cells[1].Value;
            }
        }

 private void dataGridViewInOut_DragDrop(object sender, DragEventArgs e)
        {
            DataGridViewRow row = e.Data.GetData(typeof(DataGridViewRow)) as DataGridViewRow;
            if (row != null)
            {
                Point client_point = dataGridViewInOut.PointToClient(new Point(e.X, e.Y));
                DataGridView.HitTestInfo hti = dataGridViewInOut.HitTest(client_point.X, client_point.Y);
                DataGridViewCell target_cell = dataGridViewInOut[hti.ColumnIndex, hti.RowIndex];
                target_cell.Value = row.Cells[0].Value;
            }
        }