Unity is a registered XDG environment . Unity uses the GNOME login sound
so its .desktop file would ideally add 'Unity' to its OnlyShowIn value.
This isn't particularly relevant this second, but will be once the patch in GNOME bug 653440 lands.
Created attachment 48653 [details] [review]
Just out of curiosity, is there a spec for XDG_CURRENT_DESKTOP?
It's been discussed several times on the xdg list, but isn't in a spec yet.