code: @Override
      public void onClick()
      {
          final UIStructurBrowser structurBrowser = (UIStructurBrowser) getDefaultModelObject();
          // toggle sort direction
          if (structurBrowser.getSortDirection() == SortDirection.NONE
                          || structurBrowser.getSortDirection() == SortDirection.DESCENDING) {
              structurBrowser.setSortDirection(SortDirection.ASCENDING);
          } else {
              structurBrowser.setSortDirection(SortDirection.DESCENDING);
          }
          structurBrowser.sort();
          try {
              final Page page;
              if (structurBrowser instanceof UIFieldStructurBrowser) {
                  page = new FormPage(Model.of((UIForm) getPage().getDefaultModelObject()));
              } else {
                  page = new StructurBrowserPage(Model.of(structurBrowser));
              }
              getRequestCycle().setResponsePage(page);
          } catch (final EFapsException e) {
              getRequestCycle().setResponsePage(new ErrorPage(e));
          }
      }
docs: On click the model is sorted and a new page with this model as response
  rendered.