private function _getParentTabSlug($sPageSlug, $sTabSlug)
{
$_sParentTabSlug = $this->getElement($this->oFactory->oProp->aInPageTabs, array($sPageSlug, $sTabSlug, 'parent_tab_slug'), $sTabSlug);
return isset($this->oFactory->oProp->aInPageTabs[$sPageSlug][$_sParentTabSlug]['show_in_page_tab']) && $this->oFactory->oProp->aInPageTabs[$sPageSlug][$_sParentTabSlug]['show_in_page_tab'] ? $_sParentTabSlug : $sTabSlug;
}