code: def on_select_mean_type_box(self, event):
          
          new_mean_type = self.mean_type_box.GetValue()
          if new_mean_type == "None":
              self.parent.clear_high_level_pars()
          self.parent.mean_type_box.SetStringSelection(new_mean_type)
          self.parent.onSelect_mean_type_box(event)
docs: set parent Zeq_GUI to reflect change in this box and change the
          @param: event -> the wx.ComboBoxEvent that triggered this function