Under some circumstances the Vector tabs collaps and uncollaps in an infinite loop. I could reproduce with
- window.innerWidth === 1027
- enabled VisualEditor
- on page with pending changes
- a German interface
The loop is:
- "Lesen", "Ungesichtete Änderungen", and "Bearbeiten" are visible
- "Quelltext bearbeiten" starts to uncollaps
- When "Quelltext be" is visible, the right tabs drop down (like it is on very narrow screens)
- "Quelltext bearbeiten" starts to collaps, the right tabs move up again
- When it is fully collapsed, the cycle begins again.
At no time the "Quelltext bearbeiten" tab is moved into the "more" dropdown.