public function defaultModel($model = null)
    {
        if ($model !== null) {
            $this->_defaultModel = $model;
        }
        if ($this->_defaultModel) {
            return $this->_defaultModel;
        }
        if (!$this->_View->getRequest()->getParam('paging')) {
            return null;
        }
        list($this->_defaultModel) = array_keys($this->_View->getRequest()->getParam('paging'));

        return $this->_defaultModel;
    }