anchor.diff:    enableOfficialBranding ? false
   }:
   
  -let version = "31.2.0"; in
  +let version = "31.4.0"; in
   let verName = "${version}"; in
   
   stdenv.mkDerivation rec {
  
positive.code:       "--disable-pulseaudio"
      ] ++ (if debugBuild then [ "--enable-debug" "--enable-profiling"]
                          else [ "--disable-debug" "--enable-release"
                                 "--enable-optimize" "--enable-strip" ])
      ++ [
        "--disable-javaxpcom"
        "--enable-stdcxx-compat" # Avoid dependency on libstdc++ 4.7
      ]
      ++ stdenv.lib.optional enableOfficialBranding "--enable-official-branding";
  
    configurePhase = ''
      patchShebangs .
  
      echo '${stdenv.lib.concatMapStrings (s : "ac_add_options ${s}\n") configureFlags}' > .mozconfig
      echo "ac_add_options --prefix='$out'" >> .mozconfig
      echo "mk_add_options MOZ_MAKE_FLAGS='-j$NIX_BUILD_CORES'" >> .mozconfig
  
      make ${makeFlags} configure
    '';
  
    makeFlags = "-f client.mk";
    buildFlags = "build";
  
    postInstall =
      ''
        rm -rf $out/include $out/lib/thunderbird-devel-* $out/share/idl
  
        # Create a desktop item.
  
negative.code: { stdenv, fetchurl, pkgconfig, which, m4, gtk, pango, perl, python, zip, libIDL
  , libjpeg, libpng, zlib, dbus, dbus_glib, bzip2, xlibs
  , freetype, fontconfig, file, alsaLib, nspr, nss, libnotify
  , yasm, mesa, sqlite, unzip, makeWrapper, pysqlite
  