Suddenly unable to scroll in backend
I think I found the problem.
Sometimes i can not scroll in backend. This seems to always occur when I change the language in left panel (sitemap - see screenshot). Tested in dev and master (latest version of Chrome and Firefox).
After reloading the sitemap, scrolling no longer works anywhere in backend.
Please note: Sitemap refresh in a QUI-Popup does not cause this problem (like in ContentSwitcher control).
I hope this helps you to fix this very annoying problem ;)