User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b4pre) Gecko/2008021804 Minefield/3.0b4pre Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b4pre) Gecko/2008021804 Minefield/3.0b4pre I think the favicon and the throbber should be combined. During loading of webpages, it displays a default page icon anyways. Putting the throbber in the favicon area of the address bar not only saves space, but it also allows them to check on the loading status in the most common area that they'll look for operations dealing with Firefox (namely the upper left corner). Besides, it seems like the current throbber in the upper right corner is no longer showering the global status of loading pages anyway, but rather only throbbing for the current tab. Combining the favicon and the throbber will help emphasize this fact. Reproducible: Always