Forum:Collapsible sidebar

Does anyone know what manipulates the collapsible sidebar in Monobook? I was under the impression that "portlet" element would do the job, but it's not really. Compare the following sidebars in Halo Fan Fiction Wiki (collapsible) and Dead Space (not collapsible). Maybe some specific mediawiki page that I need to create/add/change? — subtank  ( 7alk ) 12:02, September 11, 2011 (UTC)