anchor.diff: -{ lib, stdenv, fetchurl, pkg-config, intltool, libxfce4util, xfce4-panel, libxfce4ui,
  -  gtk2, exo, gnutls, libgcrypt, xfce }:
  +{ lib, stdenv, fetchurl, pkg-config, intltool, xfce4-panel, libxfce4ui,
  +  exo, gnutls, libgcrypt, xfce }:
   
   let
     category = "panel-plugins";
  
positive.code: 
  stdenv.mkDerivation rec {
    pname  = "xfce4-mailwatch-plugin";
    version = "1.2.0";
  
    src = fetchurl {
      url = "mirror://xfce/src/${category}/${pname}/${lib.versions.majorMinor version}/${pname}-${version}.tar.bz2";
      sha256 = "1bfw3smwivr9mzdyq768biqrl4aq94zqi3xjzq6kqnd8561cqjk2";
    };
  
    nativeBuildInputs = [
  
negative.code:   ];
  
    buildInputs = [
      libxfce4ui
      xfce4-panel
      exo
      gnutls
      libgcrypt
    ];
  