bug#51202: peek broken on foreign distro

[zimoun]

Hi,

On foreign distro using Guix fb32a38, I get  this error, from xterm:

--8<---------------cut here---------------start------------->8---
$ guix environment --ad-hoc peek -- peek

(peek:31579): GLib-GIO-ERROR **: 11:32:59.181: Settings schema 
'org.gnome.desktop.interface' is not installed
--8<---------------cut here---------------end--------------->8---

Inside Emacs (M-x shell), instead I get:

--8<---------------cut here---------------start------------->8---
$ guix environment --ad-hoc peek -- peek
Error: Child process exited with code 1
Unable to initialize default recording backend: Peek requires FFmpeg or running 
GNOME Shell session.
--8<---------------cut here---------------end--------------->8---

In this case, adding the package ’ffmpeg’ makes it work.  Any reason to
not propagate ’ffmpeg’ here?  Maybe ’gnome-shell’ could be propagated
instead but the sizes are really different: 797.2MiB vs 2120.1MiB.

If GNOME user really want a light peek without ffmpeg, maybe we could
create 2 variants.  WDYT?

All the best,
simon