Description of problem: gparted currently needs mtools to change FAT filesystem labels. Probably worth a Requires. Also filed upstream bug requesting support to use dosfstools' dosfslabel. May want to switch to that when it happens. http://bugzilla.gnome.org/show_bug.cgi?id=576616
I'm not inclined to add a requires for mtools for gparted. The reason being that gparted support quite a (small) number of filesystems, for which it does a runtime detection of the various tools filesystems tools. I think it is superfluous to add all these as require for the package. I believe your suggestion to upstream to use dosftools is a good one, as it seems to be install by default.