code: def on_select_show_box(self,event):
          
          self.parent.UPPER_LEVEL_SHOW=self.show_box.GetValue()
          self.parent.calculate_high_levels_data()
          self.parent.plot_high_levels_data()
docs: Changes the type of mean shown on the high levels mean plot so that single dots represent one of whatever the value of this box is.
          @param: event -> the wx.COMBOBOXEVENT that triggered this function