docs: public BasePanel makeSubScreen()
      {
          SwitchClassSub listener = new SwitchClassSub(null, null, null)
          {
              public BasePanel getSubScreen(BasePanel parentScreen, ScreenLocation screenLocation, Map<String, Object> properties, int screenNo)
              {
                  BasePanel subScreen = super.getSubScreen(parentScreen, screenLocation, properties, screenNo);
                  if (subScreen != null)
                  {
                      Record record = subScreen.getMainRecord();
                      if (record != null)
                          if (record != getMainRecord())
                      {   // Make sure classinfo is updated when detail is update, so I can write on exit
                          record.addListener(new DateChangedHandler((DateTimeField)getMainRecord().getField(ClassInfo.LAST_CHANGED)));
                      }
                  }
                  return subScreen;
              }
              
          };
          this.getScreenRecord().getField(ClassVars.CLASS_KEY).addListener(listener);
          this.getScreenRecord().getField(ClassVars.CLASS_KEY).setValue(5, DBConstants.DISPLAY, DBConstants.SCREEN_MOVE);
          return (BasePanel)listener.getSubScreen();
      }