public function reorderable()
    {
        if ($this->reorderable === null) {
            if (isset($this->dualSelectOptions['reorderable'])) {
                $this->reorderable = boolval($this->dualSelectOptions['reorderable']);
            } else {
                $this->reorderable = false;
            }
        }

        return $this->reorderable;
    }