Spotted on https://www.mediawiki.org/wiki/Project:Support_desk

I wanted to revert edits made to the header, but it wasn't possible. If I click the "undo" link in the page's history, i got the undo form (I think it's the undo form), but the flow-ui-load-overlay wasn't removed, which made it impossible to click anything. After removign the overlay (...) with the browser console, I could save the new header without any problems.