public function dropdown($title, $url, \Closure $callback, $order = 0, array $attributes = array())
    {
        $properties = compact('title', 'url', 'order', 'attributes');

        if (func_num_args() == 4) {
            $arguments = func_get_args();

            $title = array_get($arguments, 0);
            $attributes = array_get($arguments, 3);

            $properties = compact('title', 'attributes');
        }

        $child = static::make($properties);

        call_user_func($callback, $child);

        $this->childs[] = $child;

        return $child;
    }