This happened on MediaWiki, he.wiki and en.wiki on Chrome.
Open some article for editing (preferably a long one so the effect is seen)
add some text in the middle or end, mark it and make it a "Heading".
Observed result: The text turns into a heading, but the entire edit section scrolls up to the top of the page. This is especially annoying when the page is long and when the edit is done in the middle.
Version: unspecified
Severity: minor
I just checked the editor on Firefox 22.0, and it does not scroll there (works as expected). The bug seems to be in Chrome only.
If it helps, that's the UserAgent for my Chrome browser:
Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.116 Safari/537.36
Change 72768 had a related patch set uploaded by Robmoen:
Affordances for MenuWidget to be optionally focusable.
Change 72768 merged by jenkins-bot:
Affordances for MenuWidget to be optionally focusable.
This is now fixed by the above commit; we'll get it deployed soon. Sorry for the disruption.