Comment 17 for bug 889889

> /usr/share/software-center/images/spinner.gif

Obviously, this is for an animation, which PNG and SVG alone cannot provide. (If an animation happens to have rotational symmetry, you can use CSS+JavaScript to rotate it, but that's needlessly complicated.) The same is probably true for all the other filenames in the list that contain "animated", "spinner", or "throbber". Unfortunately, GDK does not have any animated bitmap format built-in, and it depends on libpng which doesn't either. <https://bugzilla.gnome.org/show_bug.cgi?id=151281>