public function getHiddenVars()
 {
     $arr = parent::getHiddenVars();
     if ($this->redirect_url) {
         $arr['amember_redirect_url'] = $this->redirect_url;
     }
     if ($f = $this->_request->getFiltered('saved_form')) {
         $arr['saved_form'] = $f;
     }
     return $arr;
 }