public function getRenderFactory(CNabuRenderInterfaceDescriptor $nb_descriptor)
    {
        if (!($retval = $this->nb_render_factory_list->getItem($nb_descriptor->getKey()))) {
            $retval = $this->nb_render_factory_list->addItem(new CNabuRenderFactory($nb_descriptor));
        }

        return $retval;
    }