anchor.diff:  
   { lib, stdenv, pkgconfig, pango, perl, python2, python3, zip
   , libjpeg, zlib, dbus, dbus-glib, bzip2, xorg
  -, freetype, fontconfig, file, nspr, nss, libnotify
  +, freetype, fontconfig, file, nspr, nss, nss_3_53, libnotify
   , yasm, libGLU, libGL, sqlite, unzip, makeWrapper
   , hunspell, libXdamage, libevent, libstartup_notification
   , libvpx_1_8
  
positive.code:     # yasm can potentially be removed in future versions
      # https://bugzilla.mozilla.org/show_bug.cgi?id=1501796
      # https://groups.google.com/forum/#!msg/mozilla.dev.platform/o-8levmLU80/SM_zQvfzCQAJ
      nspr nss
    ]
    ++ lib.optional  alsaSupport alsaLib
    ++ lib.optional  pulseaudioSupport libpulseaudio # only headers are needed
  
negative.code:   # 78 ESR won't build with rustc 1.47
    inherit (if lib.versionAtLeast ffversion "82" then rustPackages else rustPackages_1_45)
      rustc cargo;
  
    nss_pkg = if lib.versionOlder ffversion "83" then nss_3_53 else nss;
  in
  
  buildStdenv.mkDerivation ({
  