anchor.diff:  { theme ? null, stdenv, fetchurl, dpkg, makeWrapper , alsaLib, atk, cairo,
   cups, curl, dbus, expat, fontconfig, freetype, glib , gnome2, gtk3, gdk_pixbuf,
   libappindicator-gtk3, libnotify, libxcb, nspr, nss, pango , systemd, xorg,
  -at-spi2-atk, libuuid
  +at-spi2-atk, libuuid, nodePackages
   }:
   
   let
  
positive.code:       --replace /usr/bin/ $out/bin/ \
        --replace /usr/share/ $out/share/
    '' + stdenv.lib.optionalString (theme != null) ''
      cat <<EOF >> $out/lib/slack/resources/app.asar.unpacked/src/static/ssb-interop.js
      var fs = require('fs');
      document.addEventListener('DOMContentLoaded', function() {
      let tt__customCss = ".menu ul li a:not(.inline_menu_link) {color: #fff !important;}"
        fs.readFile('${theme}/theme.css', 'utf8', function(err, css) {
              \$("<style></style>").appendTo('head').html(css + tt__customCss);
              \$("<style></style>").appendTo('head').html('#reply_container.upload_in_threads .inline_message_input_container {background: padding-box #545454}');
              \$("<style></style>").appendTo('head').html('.p-channel_sidebar {background: #363636 !important}');
              \$("<style></style>").appendTo('head').html('#client_body:not(.onboarding):not(.feature_global_nav_layout):before {background: inherit;}');
        });
      });
      EOF
    '';
  
    meta = with stdenv.lib; {
  
negative.code:     gtk3  # needed for GSETTINGS_SCHEMAS_PATH
    ];
  
    nativeBuildInputs = [ makeWrapper nodePackages.asar ];
  
    dontUnpack = true;
    buildCommand = ''
  