bug#47204: DrRacket fonts issue

[Philip McGrath]

Hi Jack,

I haven't been able to reproduce this yet, but I'm on a foreign distro, 
and I don't have any fonts explicitly installed via Guix. (For that 
matter, I don't have a monitor connected, just now: I've done this with 
X forwarding.) I do have a few debugging ideas you could try and see if 
they turn up anything interesting:

  - Setting the FC_DEBUG environment variable while running can cause
    fontconfig to emit debugging information to standard output.[1]

  - The command `racket -e "(require racket/draw)" -e "(get-face-list)"`
    should print the list of font family names Racket was able to
    discover.

  - If you start DrRacket at the command line, foreign libraries
    have been known to write useful information to standard out/error.
    Similarly, if, rather than using the `drracket` launcher, you use a
    command like `racket -l drracket`, then you can add additional flags
    like "-W" to control Racket's logging system.[2] Racket converts
    glib "log domains"[3] to "topics" in Racket's logging system, which
    might help get information from some of the related libraries.[4]
    (You can also view Racket logging within DrRacket, but it might be
    too late to help with this issue.)

  - You can try changing the font in DrRacket: if you use the
    "Edit|Preferences…" menu item, the "Font" tab is the first one,
    conveniently.

Hope some of this helps!

-Philip

[1]: https://www.freedesktop.org/software/fontconfig/fontconfig-user.html
[2]: https://docs.racket-lang.org/reference/logging.html
[3]: 
https://developer.gnome.org/glib/stable/glib-Message-Logging.html#log-domains
[4]: https://docs.racket-lang.org/draw/libs.html