Thread:Project:Support desk/SideBar menu opens then automatically collapses/reply (5)

I see the problem in the heimatverein-gymnich wiki as well. The wiki uses the Vector skin. No code concerning that part of MediaWiki on Common.js and on Vector.js.

In earlier versions the collapsing was part of the extension (not the skin!) of the extension Vector. In MediaWiki 1.22 this extension has been merged into the MediaWiki core. Now the extension is superfluous. However, your Special:Version page shows that you still have the Vector extension activated. You should remove the Vector extension from LocalSettings.php and the files from the extensions/ folder!

I am pretty sure this improves, if not solves the problem!