anchor.diff:  { lib, stdenv
   , fetchFromGitHub
   , sassc
  -, autoreconfHook
  +, meson
  +, ninja
   , pkg-config
   , gtk3
  +, glib
   , gnome
   , gtk-engine-murrine
   , optipng
  
positive.code: 
  stdenv.mkDerivation rec {
    pname = "arc-theme";
    version = "20210127";
  
    src = fetchFromGitHub {
      owner = "jnsh";
      repo = pname;
      rev = version;
      sha256 = "sha256-P7YZTD5bAWNWepL7qsZZAMf8ujzNbHOj/SLx8Fw3bi4=";
    };
  
    nativeBuildInputs = [
      autoreconfHook
      pkg-config
      sassc
      optipng
      inkscape
      gtk3
    ];
  
    propagatedUserEnvPkgs = [
  
negative.code:     gtk-engine-murrine
    ];
  
    preBuild = ''
      # Shut up inkscape's warnings about creating profile directory
      export HOME="$NIX_BUILD_ROOT"
    '';
  
    mesonFlags = [
      "-Dthemes=cinnamon,gnome-shell,gtk2,gtk3,plank,xfwm"
      "-Dvariants=light,darker,dark,lighter"
      "-Dcinnamon_version=${cinnamon.cinnamon-common.version}"
      "-Dgnome_shell_version=${gnome.gnome-shell.version}"
      "-Dgtk3_version=${gtk3.version}"
      # You will need to patch gdm to make use of this.
      "-Dgnome_shell_gresource=true"
    ];
  
    meta = with lib; {
      description = "Flat theme with transparent elements for GTK 3, GTK 2 and Gnome Shell";
  