gtk+ 2 doesn't recognize default themes

[shosti]

Issue description

gtk+ 2 comes with a few default themes ("Default", "Raleigh", and "Emacs"), but by default gtk apps don't seem to be able to pick them up.

Steps to reproduce

1. Install chromium (through /etc/nixos/configuration.nix)
2. echo 'gtk-key-theme-name="Emacs"' >> ~/.gtkrc-2.0
3. Launch chromium
4. Try using Emacs keybindings (for instance, C-a in the search bar)

Expected: Uses Emacs keybindings
Actual: Uses default keybindings

(I was able to work around the issue by copying from the nix store for gtk to ~/.themes.)

Technical details

• System: NixOS 17.03.1152.22da5d0246 (Gorilla)
• Nix version: nix-env (Nix) 1.11.8
• Nixpkgs version: "17.03.1152.22da5d0246"
• Sandboxing enabled: build-use-sandbox = false

[pbogdan]

Would be interested in this as well, currently my /etc/nixos/configuration.nix features:

  # this is needed so that gtk can find emacs key theme
  environment.extraInit = ''
    # argh
    mkdir ~/.themes/ 2>/dev/null
    ln -sf "${pkgs.gnome2.gtk}/share/themes/Emacs" ~/.themes/

    export XDG_DATA_DIRS="${pkgs.gnome3.gtk}/share:$XDG_DATA_DIRS"
  '';

:/

[Mic92]

@pbogdan and with this change it works for you?

[pbogdan]

@Mic92 yes, it does. Once I adjust .config/gtk-3.0/settings.ini and .gtkrc-2.0 to use Emacs key theme I get them working in both gtk+2 and gtk+3 apps.

[Mic92]

if you install gnome2.gtk in systemPackages or via nix-env, it will get a symlink in ~/.nix-profile/share/themes or /run/current-system/sw/share/themes. Since these directories are also in XDG_DATA_DIR, they should be picked up by applications like Chrome. This should at least work for gtk3. I am not 100% sure about gtk2 though.

[Mic92]

Just tested it and the chromium example worked for me.

[pbogdan]

IIRC gtk+2 won't search through any of $XDG_DATA_DIRS but has hardcoded list of folders ~/.themes and $GTK_DATA_PREFIX/share/themes ($GTK_DATA_PREFIX must contain a single path I think).
Did you install gtk system wide or into your profile?
The issue then is that you can't have both in a single profile due to collisions.

[pbogdan]

Some digging turned up this patch from our Guix friends 😄 - https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/patches/gtk2-theme-paths.patch - which enables gtk+2 to search through $XDG_DATA_DIRS

[Mic92]

I had it in my profile, but system wide should working the same following the logic. Also just using ~/.gtkrc-2.0 was enough. You also have to really kill chromium. It tends to leave running background processes.

[pbogdan]

Odd, gtk+2 doesn't look at $XDG_DATA_DIRS AFAIK. What's your $GTK_DATA_PREFIX set to?

[Mic92]

Seems like I that this at some point:

$ echo $GTK_DATA_PREFIX                        
/run/current-system/sw

[pbogdan]

Anything under /run/current-system/sw/share/themes/ ? I would guess that's where it gets picked up from there though it would be strange for a package installed via user profile. Unless you have anything under ~/.themes perhaps?

[shosti]

All installations for me are global, and I'm using xmonad (gnome isn't installed and I'd like to avoid installing it if possible). It looks like the themes don't end up in /run/current-system/sw/share/themes/:

~ $ echo $XDG_DATA_DIRS
/nix/store/wgghc6zvhc1jjy8h76czp6z16kg0qk3g-emacs-25.1/share:/nix/store/zp3zcinsx7d5fa6mc407pz1bndk7wl2v-gtk+3-3.22.8/share/gsettings-schemas/gtk+3-3.22.8:/nix/store/9755bvfhzln5yrbjnjarl6p5vczmsgnl-gsettings-desktop-schemas-3.22.0/share/gsettings-schemas/gsettings-desktop-schemas-3.22.0:/nix/store/wgghc6zvhc1jjy8h76czp6z16kg0qk3g-emacs-25.1/share:/nix/store/zp3zcinsx7d5fa6mc407pz1bndk7wl2v-gtk+3-3.22.8/share/gsettings-schemas/gtk+3-3.22.8:/nix/store/9755bvfhzln5yrbjnjarl6p5vczmsgnl-gsettings-desktop-schemas-3.22.0/share/gsettings-schemas/gsettings-desktop-schemas-3.22.0:/run/opengl-driver/share:/home/shosti/.nix-profile/share:/nix/var/nix/profiles/default/share:/run/current-system/sw/share
~ $ echo $GTK_DATA_PREFIX
/nix/store/d0f84nizpwdj6aiss7051ixn0aqakqwh-system-path
~ $ ls /run/current-system/sw/share/themes/
~ $ 

[Mic92]

You do not need to install gnome, but gnome.gtk2 in systemPackages, which is already there (but not linked in /nix/store/d0f84nizpwdj6aiss7051ixn0aqakqwh-system-path) if you already have any gtk2 application like chromium.

[shosti]

Oh, sorry, misunderstood. It's definitely not linked in my case, either to /run/current-system/sw/share/themes/, or to $GTK_DATA_PREFIX/share/themes/.

[Mic92]

I mean you have to explicitly add it to systemPackages, also it already lives in /nix/store.

[shosti]

Oh, actually that seems to have done the trick. Incidentally, I'd tried that earlier with gtk2-x11 but it didn't work—what is the difference between the two packages? I still feel like it might make sense to either document the behavior better or to auto-link when it isn't explicitly included in `systemPackages` though.

[shosti]

Actually I spoke too soon--it is linked to /run/current-system/sw/share/themes/ but chromium still isn't picking it up.

[Mic92]

this is actually the same as the system-path package:

$ ls -al /run/current-system/sw
lrwxrwxrwx 1 root root 55 Jan  1  1970 /run/current-system/sw -> /nix/store/rqgbn2syh1d5av1kb4sl5dkdsi7zmizh-system-path/

[pbogdan]

@shosti shot in the dark - you wouldn't happen to be running xsettingsd or another settings daemon like gnome-settings-daemon? Does stop / starting that help at all?

And sorry to bug - @Mic92 @shosti what display manager you are using?

[shosti]

Oh, actually I got it working--the problem was that GTK_DATA_PREFIX didn't get reset on nix-rebuild switch, so I had to log out and log in (it was pointing to the old system path).

(For the record, using xmonad.)

[Mic92]

@pbogdan https://github.com/Mic92/nixos-configuration/blob/master/configuration.nix#L44

[Mic92]

I will also port the GUIX patch to nixos: #25881