1. Go to a page with an animated gif (http://tinderbox.mozilla.org/showbuilds.cgi?tree=MozillaTest usually has burning) 2. Hold shift and click reload At this point the animated gifs are no longer animating. Testing hourlies says that this was caused by bug 296818 Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.9a9pre) Gecko/2007101904 Minefield/3.0a9pre ID:2007101904
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a9pre) Gecko/2007101923 Minefield/3.0a9pre I see it sometimes as soon as I load the site. When I load the site nothing is moving but when I scroll horizontally they start animating when they enter the viewport. Scrolling vertically makes no difference.