Are rar and zip files supposed to have thumbnails in Nautilus? If so, I don't have them (cbr/cbz works fine).
Since I don't use cbr/cbz I would like to see this feature implemented. I hope this can be done by editing the comicthumb file, so if somebody knows how to do it by altering the already existing thumbnailer feature for cbr/cbz I would try to do it manually (I should request it as a feature in the next release as well).
By the way, Comix has worked well opening any file and has been recently updated. This is the only problem I've had.