Last modified: 2014-05-28 14:05:44 UTC
This is talking about the "Watch" button (tab) in Vector when a page is being watched (AJAX waiting for response). Try clicking on it to reproduce and if your network is too fast, $('#ca-watch a, #ca-unwatch a').addClass('loading') to make it "loading forever".
Tested with FF 17.0.1 ESR, it's ugly (sorry for wording). In Chrome it's a smooth and beautiful spin :)
Bug 65434 comes to my mind; similar/same reason?
The same. *** This bug has been marked as a duplicate of bug 65434 ***