change combobox property using personal format action

Hello,

I have a combobox that is not modifiable so the user can easily navigate through the list by pressing the first caracter.

This combobox contains an element that should set the combobox property as modifiable ("Other please specity").

I have manage to code the event so it change the property of the combobox but it won't actually change he property until it lose the focus. So i am force to set the focus to another field for it to work.

p.s: i tried setting the focus on the other field and then back to the combobox and it won't change the property either.

	var liste = getFunctionList();
	var value_idx = liste.indexOf(event.change);
	if (event.willCommit == false) {
		if (value_idx == -1) {
		
		}
		else if (value_idx == liste.length -1) {
			event.target.editable = true;
			getField("1.1f.Unite").setFocus();
		}
		else if ( value_idx < liste.length -2 )  {
			event.target.editable = false;
			getField("1.1f.Unite").setFocus();			
		}

	}

 Is there an event or a way that would allow me to set the combobox as modifiable when the last item is selected else set it as non modifiable without having to quit the combobox?

Thanks