bug#38046: Font Issues in GNOME

[Leo Prikler]

> In many places, I started to see the contents as 'boxes' instead of
> actual characters. For example, System Monitor and Gajim. Please find
> the attachments with this email.

I've had similar issues and then consulted the manual, where I saw the
following snippet:
> After installing fonts you may have to refresh the font cache to use
> them in applications.  The same applies when applications installed
> via Guix do not seem to find fonts.  To force rebuilding of the font
> cache run ‘fc-cache -rv’.
It seems the issue is a stale fontconfig cache.  Specifically, the
italic versions of Cantarell seem to cause this behaviour (as Cantarell
was updated along with everything else in Gnome 3.30).  I fixed it on
my machine by running ‘fc-cache -rv’ both as user to fix local caches
and as super-user to fix system caches.  Perhaps this also overlaps
with [1].

Regards,

Leo

[1] guix-devel mailing list, Stateful System Directories. 
https://lists.gnu.org/archive/html/guix-devel/2019-10/msg00421.html