docs: public int bookmarkToIndex(Object bookmark)
      {
          if (bookmark != null)
              if (m_mapCache != null)
          {
              for (int iRowIndex = 0; iRowIndex < m_mapCache.size(); iRowIndex++)
              {
                  Object data = m_mapCache.get(iRowIndex);
                  if (data instanceof Vector)
                  {
                      Object objID = ((Vector)data).get(0);
                      if (bookmark.equals(objID))
                          return iRowIndex;
                  }
              }
          }
          return -1;  // Not found
      }