anchor.diff:    postFixup = ''
       wrapProgram $out/bin/qutebrowser \
         "''${gappsWrapperArgs[@]}" \
  -      "''${qtWrapperArgs[@]}"
  +      "''${qtWrapperArgs[@]}" \
  +      --add-flags '--backend ${backend}'
     '';
   
     meta = with stdenv.lib; {
  
positive.code:   ];
  
    propagatedBuildInputs = with python3Packages; [
      pyyaml pyqt5 pyqtwebengine jinja2 pygments
      pypeg2 cssutils pyopengl attrs setuptools
      # scripts and userscripts libs
      tldextract beautifulsoup4
      pyreadability pykeepass stem
    ];
  
    patches = [
      ./fix-restart.patch
    ];
  
    dontWrapGApps = true;
    dontWrapQtApps = true;
  
negative.code:     sha256 = "1fpxsw0hzahccyng08acvc7g0gk29j2x701p6w6fg1718mvcrm1q";
      stripRoot = false;
    };
  
    backendPackage =
     if backend == "webengine" then python3Packages.pyqtwebengine else
     if backend == "webkit"    then python3Packages.pyqt5_with_qtwebkit else
     throw ''
       Unknown qutebrowser backend "${backend}".
       Valid choices are qtwebengine (recommended) or qtwebkit.
     '';
  
  in mkDerivationWith python3Packages.buildPythonApplication rec {
    pname = "qutebrowser";
  