You can set the selected index property of the RepositoryItemComboBox in the InitNewRow event as follows:
private void gridView_InitNewRow(object sender, DevExpress.XtraGrid.Views.Grid.InitNewRowEventArgs e)
{
gridView.SetRowCellValue(e.RowHandle, viewAddColumns.Columns["colFieldName"], (((RepositoryItemComboBox)gridView.Columns["colFieldName"].ColumnEdit).Items[0]));
}
You can also retrieve the value of the selectedindex of the RepositoryItemComboBox by handling SelectedIndexChanged event of the same. as:
((RepositoryItemComboBox)gridView.Columns["ColName"].ColumnEdit).SelectedIndexChanged += new System.EventHandler(ColName_SelectedIndexChanged);
in load event and defining event as follows
private void ColName_SelectedIndexChanged(object sender, System.EventArgs e)
{
int i = ((DevExpress.XtraEditors.ComboBoxEdit)sender).SelectedIndex;
}