public function displayList($id_lang = NULL)
 {
     global $currentIndex;
     $tmp_currentIndex = $currentIndex;
     if ($id_category = intval(Tools::getValue('id_category'))) {
         $currentIndex .= '&id_category=' . $id_category;
     }
     parent::displayList($id_lang);
     $currentIndex = $tmp_currentIndex;
 }