anchor.diff:  , libxslt, gst_all_1 ? null
   , withPdfReader        ? true
   , withMediaPlayback    ? true
  -, withWebEngineDefault ? true
   }:
   
   assert withMediaPlayback -> gst_all_1 != null;
  
positive.code:     done
    '';
  
    postFixup = lib.optionalString (! withWebEngineDefault) ''
      wrapProgram $out/bin/qutebrowser --add-flags "--backend webkit"
    '';
  
    meta = with stdenv.lib; {
      homepage    = https://github.com/The-Compiler/qutebrowser;
      description = "Keyboard-focused browser with a minimal GUI";
  
negative.code:   ] ++ lib.optionals withMediaPlayback (with gst_all_1; [
      gst-plugins-base gst-plugins-good
      gst-plugins-bad gst-plugins-ugly gst-libav
    ]);
  
    nativeBuildInputs = [
      makeWrapper wrapGAppsHook asciidoc
  