private function _getCollapseButton($aCollapsible)
{
$_sExpand = esc_attr($this->oMsg->get('click_to_expand'));
$_sCollapse = esc_attr($this->oMsg->get('click_to_collapse'));
return $this->getAOrB('button' === $this->getElement($aCollapsible, 'type', 'box'), "<span class='admin-page-framework-collapsible-button admin-page-framework-collapsible-button-expand' title='{$_sExpand}'>►</span>" . "<span class='admin-page-framework-collapsible-button admin-page-framework-collapsible-button-collapse' title='{$_sCollapse}'>▼</span>", '');
}