- Given a page with a highlighted node at the end of the page. E.g. https://www.mediawiki.org/w/index.php?title=OOjs/Events&oldid=1090830 ends with a <syntaxhighlight> block.
- Open another tab and copy a simple heading and line of text into the clipboard.
- Back to the main tab, focus the slug and paste.
- Content area is visually distorted (left margin is gone) due to the surface documentNode having been replaced with a strange subtree. There's no uncaught exception. Reproducible on mediawiki.org and latest git master.
Note that the documentNode element has disappeared (unwrapped?), and in the user interface the margin on the left side is no longer present.