anchor.diff:  { stdenv, fetchurl, makeDesktopItem, makeWrapper
  -, dbus_libs, gcc, glib, libdrm, libffi, libICE, librsync, libSM
  +, dbus_libs, gcc, glib, libdrm, libffi, libICE, libSM
   , libX11, libXmu, ncurses, popt, qt5, zlib
   }:
   
  
positive.code: # note: the resulting program has to be invoced as
  # 'dropbox' because the internal python engine takes
  # uses the name of the program as starting point.
  #
  # todo: dropbox is shipped with some copies of libraries.
  # replace these libraries with the appropriate ones in
  # nixpkgs.
  
  let
    arch = if stdenv.system == "x86_64-linux" then "x86_64"
  
negative.code: 
    ldpath = stdenv.lib.makeSearchPath "lib"
      [
        dbus_libs gcc glib libdrm libffi libICE libSM libX11
        libXmu ncurses popt qt5.base qt5.declarative qt5.webkit
        zlib
      ];
  