Comment 5 for bug 1408214

Ah, yes, it is from the Ubuntu repos. Sorry, my bad.

I checked the package and indeed, it depends (doesn't just simply recommends) gnome-sushi. Which is weird, for instance, the ubuntu-desktop meta-package doesn't enforce depends and you can remove non-important apps installed by default without removing the meta package.

Unfortunately, this means that you can't install gloobus-preview without removing gnome-sushi and thus, ubuntu-gnome-desktop. This can only be fixed by the Ubuntu GNOME devs, by moving gnome-sushi from "depends" to "recommends".