# File gtk/sample/gtk-demo/changedisplay.rb, line 382
    def add_display(display)
      iter = @display_model.append
      iter.set_value(DISPLAY_COLUMN_NAME, display.name)
      iter.set_value(DISPLAY_COLUMN_DISPLAY, display)

      handler_id = display.signal_connect('closed') do
        display_closed_cb(display)
      end

      signal_connect('destroy') do
        display.signal_handler_disconnect(handler_id)
      end
    end