@Override
 public void go(JPanel menuLeft) {
   menuLeft.removeAll();
   menuLeft.add(display.getPanel());
   menuLeft.revalidate();
   menuLeft.repaint();
 }
  private void fetchOrderCategories() {
    Label loading = new Label("Loading orders ...");
    display.getPanel().add(loading);

    rpcService.getOrderCategories(
        MainPresenter.uploadID,
        new AsyncCallback<ArrayList<OrderCategory>>() {

          @Override
          public void onSuccess(ArrayList<OrderCategory> result) {
            display.getPanel().clear();
            for (OrderCategory category : result) {
              new SingleOrderSetPresenter(
                      new SingleOrderSetView(category), rpcService, globalEventBus)
                  .go(display.getPanel());
            }
          }

          @Override
          public void onFailure(Throwable caught) {
            Window.alert(
                "Server Error: failed to get order categories. \n\n" + caught.getMessage());
          }
        });
  }