How to populate a ComboBox After adding new item
===

I'm developing a SSIS control flow task.  On my UI I have a combobox which displays a list of avaialble user variables as well as the ability add a new variable.  I'm able to add the variable successfully but I can't see it in my combobox even after I repopulate the datasource.  On the SelectionChangeCommitted event I am saving the combobox selection.  If the user selects to add a new SSIS user variable then they are prompted to within this method.  The variable is saved and then I am repopulating the datasource of the combobox.  Although my new variable isn't being shown in the drop down list.  Should I be repopulating the combobox on a different event?

An example of the code I am using below.

      private List<string> FillVariablesList()
        {
            List<string> Variables = new List<string>();
            Variables.Add("");
            Variables.Add(New_Variable);
            foreach (Variable v in this.theTaskHost.Variables)
            {
                if (!v.SystemVariable && v.DataType == TypeCode.String)
                    Variables.Add(v.Name);
            }

            return Variables;
        }

     combobox.datasource = FillVariables();