User Agent: Opera/9.80 (Windows NT 6.1; WOW64; U; en) Presto/2.10.289 Version/12.02
Steps to reproduce:
This is demonstrated in the following JSFiddle: http://jsfiddle.net/F5tdB/ and described in the following StackOverflow question: http://stackoverflow.com/questions/13040897/firefox-scrollbar-resets-incorrectly In the SO question there's also a workaround by one of the community members.
1. Get an element with overflow:auto and some vertically overflowing contents, then scroll it down a bit;
2. Hide the element (display: none);
3. Remove contents
4. Show the element (it's empty now)
5. Re-add the same contents (it's scrolled now, just as it was before)
The contents got scrolled to the top, as is proper, but the vertical scrollbar itself stayed in the old (scrolled down) position.
The vertical scrollbar should also have scrolled to the top.
Created attachment 674497 [details]
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9a1) Gecko/20060407 Firefox/3.0a1
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9a1) Gecko/20060408 Firefox/3.0a1
Bug 331607 - scroll position can not be retained in overflowing RTL blocks
Why is Bug 331607 mentioned, and the related forum thread? This has nothing to do with RTL blocks.
(In reply to valts from comment #3)
> Why is Bug 331607 mentioned, and the related forum thread? This has nothing
> to do with RTL blocks.
This problem is a regression due to landing patch of Bug 331607.