Bugs 993870 and 949874 introduced a feature where we load the component list via AJAX when a user selects a component (they use the same JS code for this). It would be good to add a spinning wheel icon to indicate that the component list is loading. This would be especially useful for people on slower connections.
While I'm working on this, I also noted that the show_bug.cgi spinning wheel for editing a component is displayed when Javascript is disabled. That is bad, mmkay? :)
This change is now live. If there are any issues, do not reopen this bug. Instead, you should create a new bug and reference this bug. -- simon