Steps to reproduce:
Does not happen always, but frequently for me. I have noticed these conditions.
- Use tree style vertical tabs.
- Click on a link on a page to open children pages.
- Sometimes, the children tab entries are duplicated.
Example. Only the entry is duplicate in the open tabs view. It does NOT open 2 identical tabs. If you scroll down in one tab, and then view the other one, it would already be scrolled. If you close 1, the other will also close. It's just a visual issue I think.