Steps to reproduce (in Firefox):
- Go to https://de.wikipedia.org/wiki/Element_(Auszeichnungssprache)?veaction=edit.
- Edit the second syntaxhighlight-element in the section "HTML (Version 1 bis 4)"
- Note there is an "i" left of the first line of code (probably it wants to inform me about the unclosed tag).
- Hover over this "i". Note that a scrollbar on the dialog is shown (perhaps some more information about the fact that the tag is unclosed is shown below).
- Try to scroll. Once you start scrolling, you stop hovering, and the scrollbar vanishes.
In Vivaldi, in step 4 no scrollbar appears, nor does happen anything else. If hovering over the "i" is meant to show additional information, this is equally bad, and makes the "i" useless in complex situations.