bug#53379: Emacs cursor theme is not inherited from the OS when using foreign Guix

[Liliana Marie Prikler <liliana.prikler@ist.tugraz.at>]

Hi

Am Donnerstag, dem 20.01.2022 um 00:03 +0000 schrieb John Hamelink:
> Hi there,
> 
> I'm experiencing an issue with the emacs-next package on my Guix
> foreign setup where the cursor (*not* Emacs point) is very dark. It's
> perfectly legible against the default Emacs theme, but nonetheless it
> is not respecting the settings of the rest of my system. To make
> things worse, I'm currently using (and enjoying!) the modus-vivendi
> theme.
> 
> My host machine is running Arch GNU/Linux with a tiling window
> manager. I set my cursor style using xsetroot like so:
> 
> xsetroot -xcf /usr/share/icons/Adwaita/cursors/left_ptr 16
Corrected your xsetroot invocation there :P

> I tried installing the adwaita-icon-theme, gnome-themes-standard, and
> gnome-themes-extra packages in an attempt at installing the correct
> theme, but that didn't help.
> 
> I'm not entirely sure what the issue is, but after speaking with some
> folks at #guix, it was suggested to me that this may in fact be a
> bug. The other option discussed is that Guix needs its own cursor
> settings, but I'm too early on in my journey with Guix (maybe 2 hours
> of experience using the Guix binary) to know how set that up - if that
> is indeed the case, some pointers on what to read would be very
> warmly received!
It turns out this issue is actually related to another issue of Guix'
Emacs on foreign distros, which is it not finding timezones.  Since
I've found a permanent solution to both, I will close that bug and pat
myself on the back for doing so.

The main issue here is that foreign distros with systemd really cut
down on their use of environment variables, whereas Guix (System) makes
prominent use of them.  In the case of the other bug, TZDIR was unset,
in the case of yours it was XCURSOR_PATH.

Writing an override configuration file with the following contents

--8<---------------cut here---------------start------------->8---
# ~/.config/systemd/user/gnome-shell-x11.service.d/override.conf
[Service]
Environment=TZDIR='/usr/share/zoneinfo'
Environment=XCURSOR_PATH='/usr/share/icons'
--8<---------------cut here---------------end--------------->8---

fixed this for me, although I should specify that I previously only had
TZDIR set and bound XCURSOR_PATH interactively in the shell (I am
typing this just as I found the fix and haven't yet had the opportunity
to restart my X session).

Now one thing I don't quite get is the interaction with GNOME Shell. 
With my current setup as detailed above, Emacs inherits whichever
cursor was set in GNOME at the time of launch for the entire process
duration -- i.e. even if the corresponding GNOME setting changes.  
I'm pretty sure in your setup with xsetroot there's nothing else
setting the cursor, so it ought to be displayed correctly after that. 
If not, you might have to play around with cursor themes in other ways
(refer to [1]).

Cheers


[1] https://wiki.archlinux.org/title/Cursor_themes