When using tumbler with the thunar file manager to generate thumbnails,
tumblerd fails and just leaves empty files in /tmp. Inspecting the log with
dbus-monitor --session --monitor
interface=org.freedesktop.thumbnails.Thumbnailer1
yields "No thumbnailer available for "file:///foo/bar/baz.mkv"
When trying to use thunar-volman to manage removable media, thunar tells the
user in its settings that gvfs cannot be found.
Running
```
guix shell --pure dbus hicolor-icon-theme gdk-pixbuf gvfs thunar-volman thunar
-- thunar
```
has the same problem, so there's probably a bug with one of t
