On DataGrid EditingControlShowing event,
private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
try
{
if (this.dataGridView.CurrentCell.ColumnIndex == (int)Column.Col)
{
ComboBox comboBox = e.Control as ComboBox;
if (comboBox != null)
{
comboBox.SelectedIndexChanged += new EventHandler(ComboBoxIndexChanged);
}
}
return;
}
}
private void ComboBoxIndexChanged(object sender, EventArgs e)
{
dataGridView1.Rows["YourRowNumber"].Cells["YourColumnNameOrNumber"].Value;
}