code: @Override
      protected void onGetCall(Object peer, int index) {
  
          // zero categories are all (first condition)
          if (((m_backupCategories.size() == 0) && (size() != 0)) || !(containsAll(m_backupCategories))) {
              ((CmsSearchParameters)peer).setSearchPage(1);
          }
      }
docs: Set the search page of the peer Object
  (<code>{@link org.opencms.search.CmsSearch#setSearchPage(int)}</code>)
  to zero if the internal backup list of categories (taken at clear time which
  is triggered by <code>{@link org.opencms.workplace.CmsWidgetDialog#ACTION_SAVE}</code>)
  was empty (no restriction) and now categories are contained  or if the new
  backup list of categories is no subset of the current categories any
  more (more restrictive search than before). <p>
  
  @see org.opencms.workplace.tools.searchindex.CmsHookList#onGetCall(java.lang.Object, int)