docs: @SuppressWarnings("unchecked")
      public Collection<CmsCategory> getSelectedCategories() {
  
          Set<CmsCategory> result = new HashSet<CmsCategory>();
          if (m_isDiplayOny) {
              // in case of display only, all displayed categories are assume selected
              result.addAll((Collection<? extends CmsCategory>)getItemIds());
          } else {
              for (Entry<CmsCategory, CheckBox> entry : m_checkboxes.entrySet()) {
                  if (entry.getValue().getValue().booleanValue()) {
                      result.add(entry.getKey());
                  }
              }
          }
          return result;
      }