It would be very nice if Mozilla could be made not to animate images - animated gifs can be very distracting, and just showing the first frame would be a very welcome option - MSIE on Mac(not Win) and Opera already have this functionality, AFAIK
This is already documented in the release notes for mozilla. However, I don't know if it's in 0.7 or not. It's in more recent releases as a hidden pref.
Where? And can it be made not hidden?
See http://bugzilla.mozilla.org/show_bug.cgi?id=17686 , http://bugzilla.mozilla.org/show_bug.cgi?id=19258 and http://bugzilla.mozilla.org/show_bug.cgi?id=74169 To summarize, the way you control animation is by putting user_pref("image.animation_mode", "once"); or user_pref("image.animation_mode", "none"); into your prefs file, but in some versions of Mozilla this would not work.
Not a bug.