code: @Override
      protected void onComponentTag(final ComponentTag _tag)
      {
          super.onComponentTag(_tag);
          final UIStructurBrowser structurBrowser = (UIStructurBrowser) getDefaultModelObject();
          if (structurBrowser.getSortDirection().equals(SortDirection.ASCENDING)) {
              _tag.put("class", "sortLabelAsc");
          } else {
              _tag.put("class", "sortLabelDsc");
          }
      }
docs: On the tag the class is set.
  
  @param _tag tag to be set