nixos/displayManager: slimlock fix (#67350)

[misuzu]

Motivation for this change

Allow xautolock to lock session using loginctl lock-session and fix slimlock theme.
See #67350 for details

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-in-distress/3604/5

[misuzu]

@adisbladis @edolstra @fpletz please take a look at this.

[evenbrenden]

@misuzu did you close this because #67350 (comment) was a sufficient fix? I ran into the same issue - loginctl lock-session does not trigger xss-lock when run as a service because XDG_SESSION_ID is not set in the systemctl environment (I suppose idle hint management is broken too). I'd like to keep xss-lock as a service (and all the safety that comes with it) rather than launching it through sessionCommands. This PR does the trick and I also think it's tidy to do it the same way as home-manager does.

Would you consider reopening? Or, alternatively, would you mind if a created a new one based on it?

[misuzu]

@evenbrenden slim is no longer in nixpkgs, see #75389

[evenbrenden]

@evenbrenden slim is no longer in nixpkgs, see #75389

I tested with LightDM and it has the same issue.

[misuzu]

would you mind if a created a new one based on it?

Sure, go for it

I tested with LightDM and it has the same issue.

#67350 (comment) is still a good option for the time being

EDIT: sorry, attention issues