Hello laurent,

if you need to add a new row in the drop down list of the combo, i personaly add it to the DataScoure (DataSet, List<T>, etc)

for DataSet:

DataSet ds = (DataSet) this.myCombo.DataSource;

DataRow dr = ds.Tables[0].NewRow();

dr["MyValueColumn"] = 1; 

dr["MyTextColumn"] = "Ne row Added";

EDIT: oups, didn't add the row to the DataSet.

ds.Tables[0].Rows.Add(dr); 

for List<T>:

List<T> dl= (List<T>) this.myCombo.DataSource;

T newRow = new T (); 

 dl.Add(newRow);

* change T witht he list type ex(customer,Invoice, etc).

Hope that helped.

Nassos