DataGridView สอบถาม Event ของ Datagrid Column ที่มี Combobox ครับ

private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
        {
            ComboBox combo = e.Control as ComboBox;
            if (combo != null)
            {
                // Remove an existing event-handler, if present, to avoid 
                // adding multiple handlers when the editing control is reused.
                combo.SelectedIndexChanged -=
                new EventHandler(ComboBox_SelectedIndexChanged);

                // Add the event handler. 
                combo.SelectedIndexChanged +=
                new EventHandler(ComboBox_SelectedIndexChanged);
            }
        }

private void ComboBox_SelectedIndexChanged(object sender,EventArgs e)
        {
            int selectedIndex = ((ComboBox)sender).SelectedIndex;
            MessageBox.Show("Selected Index = " + selectedIndex); 
        }

combo.SelectedIndexChanged -= New EventHandler(ComboBox_SelectedIndexChanged)

            ' Add the event handler. 
            combo.SelectedIndexChanged += New EventHandler(ComboBox_SelectedIndexChanged)