code: func (v *ComboBox) SetActiveIter(iter *TreeIter) {
  	var cIter *C.GtkTreeIter
  	if iter != nil {
  		cIter = &iter.GtkTreeIter
  	}
  	C.gtk_combo_box_set_active_iter(v.native(), cIter)
  }
docs: // SetActiveIter is a wrapper around gtk_combo_box_set_active_iter().