Version 1.1 now posted.
With the dawn of a new day I took a fresh look at the handling of transparency as I didn't like the need for special treatment of such GIFs. Poking around deeper in the original source code I found several bugs that my special provisions worked around. Having fixed them there is no longer any need for UsesTransparency and UsesPartialFrames so these are removed from version 1.1.
If you find, or make, any GIFs that don't render correctly then please post them.