public function sendContent($includeMaster)
 {
     //show content only in preview, else a 404
     if (!Kwf_Component_Data_Root::getShowInvisible()) {
         throw new Kwf_Exception_NotFound();
     }
     parent::sendContent($includeMaster);
 }
 protected function checkAllowed()
 {
     $valid = Kwf_Media_Output_Component::isValid($this->_data->componentId);
     if ($valid == Kwf_Media_Output_IsValidInterface::ACCESS_DENIED) {
         // send non pdf content to show login-plugin
         $contentSender = new Kwf_Component_Abstract_ContentSender_Default($this->_data);
         $contentSender->sendContent(true);
         return false;
     } else {
         if ($valid == Kwf_Media_Output_IsValidInterface::INVALID) {
             throw new Kwf_Exception_NotFound();
         }
     }
     return $valid;
 }