anchor.diff: -{ stdenv, fetchgit, pkgconfig, xfce4-dev-tools, hicolor-icon-theme, xfce, wrapGAppsHook }:
  +{ stdenv, fetchFromGitLab, pkgconfig, xfce4-dev-tools, hicolor-icon-theme, xfce, wrapGAppsHook }:
   
   { category
   , pname
  
positive.code:     buildInputs = [ hicolor-icon-theme ];
      configureFlags = [ "--enable-maintainer-mode" ];
  
      src = fetchgit {
        url = "git://git.xfce.org/${category}/${pname}";
        inherit rev sha256;
      };
  
  
negative.code: 
      passthru.updateScript = xfce.updateScript {
        inherit pname version attrPath rev-prefix odd-unstable patchlevel-unstable;
        versionLister = xfce.gitLister src.meta.homepage;
      };
  
      meta = with stdenv.lib; {
        homepage = "https://gitlab.xfce.org/${category}/${pname}/about";
        license = licenses.gpl2; # some libraries are under LGPLv2+
        platforms = platforms.linux;
      };
  