Hello there. In our wiki, the sidebar contains collapsible items. When using the Revision slider, all items in the sidebar are suddenly shown expanded and the small triangle to collapse the subitems are gone. As soon as I change to any other article, the sidebar is shown correctly.
This happens under Mediawiki 1.27 as well as 1.31. I use the vector skin, and I have also installed the "CollapsibleVector" extension.