In ribbon bar control when you have a combobox how do you fire clicked event to set focus to the combobox?

The intention is that as a user navigates the menu a category change will find first combobox on the category and click it so the user can start selecting immediately . The Combo box is mared as Editable

I have tried in the Category Changed event finding if there is a combo box then

Get Handle of the combo box and get the ComboxControl with

ribboncomboboxitem lrs_item

rbb_1.GetComboBox (al_combohandle, lrs_item )

lrs_item.TriggerEvent(clicked!)

also tried lrs_item.SelectItem(li_item)  where li_item = 1 to 5