steam: add gsettings-desktop-schemas to FHS env

[Moredread]

Description of changes

Add gsettings-desktop-schemas to FHS env

Needed by Hadean Lands, which uses Lectrote, a GTK application. Without
schemas saving and loading crashes the game.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.05 Release Notes (or backporting 21.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[Moredread]

I've taken the export statement from another package that uses a fhs and sets up the schemas manually. It works but I'm not sure of this is correct for a multiarch installation.

[Artturin]

Not needed since #161739

[Moredread]

It doesn't work without it. Any idea what could cause that?

[Artturin]

Move this to commontargetpkgs and add(don't move) gtk3 there

[Moredread]

I still haven't gotten it to work.

steam-run has a very similar environment, so I used it to test a few things;

nix run -f . steam-run -- bash -c export
(...)
declare -x XDG_DATA_DIRS="/nix/store/lmpz9axrfpir2ig76vdl0nddjr3w53gv-desktops/share:/home/addy/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/home/addy/.nix-profile/share:/etc/profiles/per-user/addy/share:/nix/var/nix/profiles/default/share:/run/current-system/sw/share:/run/opengl-driver/share:/run/opengl-driver-32/share"

I.e. /usr/share is missing.

gsettings list-schemas also doesn't show any schemas

The profiles are installed though, so that worked:

nix run -f . steam-run -- ls -lah /usr/share/gsettings-schemas
(...)
dr-xr-xr-x 1 nobody nogroup  16 Jan  1  1970 gsettings-desktop-schemas-42.0
dr-xr-xr-x 1 nobody nogroup  16 Jan  1  1970 gtk+3-3.24.33

When I add /usr/share to XDG_DATA_DIRS everything works. Shouldn't it be there by default though?

[huantianad]

I can confirm @Moredread's findings, I'm currently adding gsettings-desktop-schemas and hicolor-icon-theme to steam's extraPkgs, but file pickers are still not working in my games. I get the same issues as above but using the launch command XDG_DATA_DIRS="$XDG_DATA_DIRS:/usr/share/" %command% in addition to adding the two packages fixes it. Weird~