SLiM Operation / dwm launch issue

[Paul Jewell <paul@teulu.org>]

Good afternoon,

I am using SLiM as a display manager, and have dwm installed (a 
personally modified version, which inherits from the standard guix 
version). When I set this up originally, I couldn't get in to dwm, so I 
was advised to use a .xsession file. That works fine, and logs me into 
dwm as expected. This week, I have decided to give stumpwm an airing, to 
evaluate whether I want to use it. Well, it installed without any 
issues, and is available in the list of window managers selectable with 
F1 on the login screen. However, when I selected stumpwm, I still got 
logged into dwm - no surprise there I guess, since I have the .xsession 
file launching dwm. Removing the latter, and stumpwm is launched as 
expected. However, now dwm is still available in the list, but doesn't 
launch successfully.

Digging deeper, I find both window managers have .desktop files in 
/run/current-system/profile/share/xsessions/, but when dwm is selected, 
it seems to finish immediately, as slim reloads again.

What I can confirm:
- The path for the dwm executable in the dwm.desktop file matches that 
returned from "which dwm". In my .xsession file, I don't add the path, 
only the executable.

In the guix documentation, it says "SLiM looks for session types 
described by .desktop files..." and "It also honors ~/.xsession files". 
It isn't clear to me what happens if both are present. It seems the 
.desktop files populate the options on the login screen, but once the 
user authorisation is clear, it will execute the ~/.xsession file if one 
is available. If not, then the .desktop files are used to run the wm.

Can anyone offer suggestions on how I should resolve this? I am not sure 
if there is some sort of bug which prevents dwm running with its default 
installation?

One last question: where should I look to find the slim.conf file? I am 
assuming there is one, based on the options which can be configured as 
part of the slim-service-type, but I haven't yet found its location! I 
have tried /run/current.../profile/etc, but it isn't there.

Apologies for the long post, and many thanks for reading, and your 
suggestions.