protected function renderToggleButton()
    {
        if (($toggleButton = $this->toggleButton) !== false) {
            $tag = ArrayHelper::remove($toggleButton, 'tag', 'button');
            $label = ArrayHelper::remove($toggleButton, 'label', 'Show');
            if ($tag === 'button' && !isset($toggleButton['type'])) {
                $toggleButton['type'] = 'button';
            }

            return $this->htmlHlp->tag($tag, $label, $toggleButton);
        } else {
            return null;
        }
    }