gtk: allow more granular customization

[khaneliman]

Description

This pull request refactors the GTK configuration module to improve flexibility, readability, and maintainability. Key changes include the introduction of global settings inheritance, per-version overrides for GTK2/3/4, and enhanced testing coverage for the new configuration structure.

Refactoring and Enhancements to GTK Configuration

• Global Settings Inheritance:

  • Added a mechanism for global settings (e.g., font, theme, icon theme, cursor theme) to be inherited by all GTK versions (gtk2, gtk3, gtk4).
  • Introduced helper functions like mkGtkSettings to streamline attribute set generation for GTK settings.

• Per-Version Overrides:

  • Enhanced configuration options to allow version-specific overrides for GTK2, GTK3, and GTK4. Each version can now have its own settings while optionally inheriting global defaults.

Improved Testing Structure

• Expanded Test Coverage:
  • Reorganized test files to separate global inheritance tests from per-version override tests.
  • Added new tests to validate global inheritance and per-version overrides for GTK settings and CSS.

Closes #5133
Closes #5900

Checklist

• Change is backwards compatible.

• Code formatted with nix fmt or
  nix-shell -p treefmt nixfmt-rfc-style deadnix keep-sorted --run treefmt.

• Code tested through nix-shell --pure tests -A run.all
  or nix build --reference-lock-file flake.lock ./tests#test-all using Flakes.

• Test cases updated/added. See example.

• Commit messages are formatted like

  {component}: {description}
  
  {long description}
  

  See CONTRIBUTING for more information and recent commit messages for examples.

• If this PR adds a new module

  • Added myself as module maintainer. See example.

Maintainer CC

[khaneliman]

@zowoq Do you know if the Github App needs different permissions to read the team/member list ? https://github.com/nix-community/home-manager/actions/runs/16034340501/job/45242369177?pr=7349 I was able to get it to work without the app in my fork #6921

From what I have read, it looks like the github app just needs its GraphQL permissions updated in the organization.

[MattSturgeon]

error fetching organization teams: GraphQL: Resource not accessible by integration (organization.teams)

Sounds like the app needs "Organization permissions" -> "Members" -> "Read-only"

Which I believe is configured from: https://github.com/settings/apps/home-manager-ci/permissions

(as always with app perm changes, they also need "accepting" from the repo's installation, but I assume org-owners are well aware of this 😅)

[zowoq]

Sounds like the app needs "Organization permissions" -> "Members" -> "Read-only"

Which I believe is configured from: https://github.com/settings/apps/home-manager-ci/permissions

(as always with app perm changes, they also need "accepting" from the repo's installation, but I assume org-owners are well aware of this 😅)

Done.

[khaneliman]

@zowoq sweet, it worked thanks. we will need the same thing done for the nixvim and stylix bots too

[zowoq]

we will need the same thing done for the nixvim and stylix bots too

I'll wait until we're adding the rfc39 service for these repos to update the app permissions.

[fmbearmf]

home-manager.users.<user>.gtk.gtk2.force' does not exist. Definition values:

This appears to have removed the gtk.gtk2.force option. Is there a new way of forcefully overwriting?
Sorry if this is a dumb question.

[khaneliman]

home-manager.users.<user>.gtk.gtk2.force' does not exist. Definition values:

This appears to have removed the gtk.gtk2.force option. Is there a new way of forcefully overwriting? Sorry if this is a dumb question.

That would have been an accident, it should be backwards compatible. I'll fix ASAP.

[khaneliman]

Created #7437 that should fix it @fmbearmf

[nixos-discourse]

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

https://discourse.nixos.org/t/home-manager-applies-my-gtk3-theme-to-gtk4/47826/2