code: public Set<String> getSelected() {
  
          Set<String> result = new HashSet<String>();
          int i = 0;
          for (Map.Entry<String, String> entry : m_items.entrySet()) {
              String key = entry.getKey();
              CmsCheckBox checkBox = m_checkboxes.get(i);
              if (checkBox.isChecked()) {
                  result.add(key);
              }
              i += 1;
          }
          return result;
      }
docs: Returns the set of values of the selected checkboxes.<p>
  
  @return a set of strings