I have a few archives with GIF images in them, and I noticed that no thumbnail is displayed in the thumbnail sidebar area, or the properties dialog.
This patch should fix that problem. The thumbnails sidebar loads a bit slower, as there are a couple extra function calls made for static images. This could probably be fixed with some kind of filetype check beforehand. I wasn't sure where to implement that, so I didn't.
I'm hoping to get gif animations working in the main display as well, and maybe I'll come up with something for the filetypes by then. Python is a new language for me. ^^