private void dgv_SelectionChanged(object sender, EventArgs e)
        {
            if (dgv.Rows.Count > 0 && selectionIdx > -1 && selectionIdx < dgv.Rows.Count - 1)// (dgv.SelectedRows.Count > 0))
            {

if (dgv.Rows.Count <= selectionIdx)
                    selectionIdx = dgv.Rows.Count - 1;
                dgv.Rows[selectionIdx].Selected = true;
                //dgv.CurrentCell = dgv.Rows[selectionIdx].Cells[0];
            }
        }

private void dgv_CellMouseDown(object sender, DataGridViewCellMouseEventArgs e)
        {
            if (e.RowIndex >= 0)
                selectionIdx = e.RowIndex;
        }

private void dgv_CellMouseMove(object sender, DataGridViewCellMouseEventArgs e)
        {
            if ((e.Clicks < 2) && (e.Button == MouseButtons.Left))
            {
                if ((e.ColumnIndex == -1) && (e.RowIndex > -1))
                    dgv.DoDragDrop(dgv.Rows[e.RowIndex], DragDropEffects.Move);
            }
        }

private void dgv_DragDrop(object sender, DragEventArgs e)
        {
            int idx = GetRowFromPoint(e.X, e.Y);
            if (idx < 0) return;

if (e.Data.GetDataPresent(typeof(DataGridViewRow)))
            {
                DataGridViewRow row = (DataGridViewRow)e.Data.GetData(typeof(DataGridViewRow));
                DataRow ddr = ((DataRowView)row.DataBoundItem).Row;
                DataRow nr = ((DataTable)dgv.DataSource).NewRow();

for (int i = 0; i < row.Cells.Count; i++)
                {
                    nr[i] = row.Cells[i].Value;
                }
                selectionIdx = idx;
                ((DataTable)dgv.DataSource).Rows.InsertAt(nr, idx);
                ((DataTable)dgv.DataSource).Rows.Remove(ddr);
                dgv.ClearSelection();
            }
        }

private void dgv_DragEnter(object sender, DragEventArgs e)
        {
            e.Effect = DragDropEffects.Move;
        }

private int GetRowFromPoint(int x, int y)
        {
            for (int i = 0; i < dgv.RowCount; i++)
            {
                Rectangle rec = dgv.GetRowDisplayRectangle(i, false);

if (dgv.RectangleToScreen(rec).Contains(x, y))
                    return i;
            }

return -1;
        }