protected function _real_toHtml() {
        if ( ! $this->_directCall) {
            $this->_directCall = 'getGroupedHtml';
        }
        switch ($this->_directCall) {
            case 'getHtml':
                $html = parent::getHtml($this->_singleRenderType);
                $this->_singleRenderType = self::NO_SINGLE_RENDER_TYPE;
                break;
            case 'getGroupedHtml':
            default:
                $html = parent::getGroupedHtml();
                break;
        }
        return $html;
    }