anchor.diff:  
        cat - > $out/share/gsettings-schemas/nixos-gsettings-overrides/glib-2.0/schemas/nixos-defaults.gschema.override <<- EOF
        [org.gnome.desktop.background]
  -     draw-background=true
  -     picture-options='zoom'
        picture-uri='${nixos-artwork.wallpapers.simple-dark-gray}/share/artwork/gnome/nix-wallpaper-simple-dark-gray.png'
        primary-color='#000000'
   
  
positive.code: let
  
    gsettingsOverridePackages = [
      gala
      epiphany
      elementary-settings-daemon
      gnome3.mutter
      gtk3
      plank
    ] ++ extraGSettingsOverridePackages;
  
negative.code: { stdenv, runCommand, gnome3, elementary-default-settings, nixos-artwork, glib, gala, epiphany, elementary-settings-daemon, gtk3, plank, gsettings-desktop-schemas
  , extraGSettingsOverrides ? ""
  , extraGSettingsOverridePackages ? []
  }:
  