code: def _set_combobox(self, attrname, vals, default=0):
          
          combobox = getattr(self.w, attrname)
          for val in vals:
              combobox.append_text(val)
          if default > len(vals):
              default = 0
          val = vals[default]
          combobox.show_text(val)
          return val
docs: Populate combobox with given list.