Vector tabs go wild and try to collapse and expand endlessly if 1) tab description is too long, 2) VisualEditor tries to add its tabs on runtime and 3) current viewport isn’t wide enough to show them all.
Steps to reproduce:
- Go to https://ru.wikipedia.org/wiki/User:CKoerner_(WMF)?uselang=ru with VisualEditor enabled
- Enjoy the dance (better would’ve been to fix it, though)
- https://i.imgur.com/A7YWFTy.gifv
Specs: Windows 8.1, Firefox 47, 1366×768