anchor.diff:      ++ optional enableSystemd "--with-systemd-daemon"
       ++ optional enableGTK3 "--with-gtk";
   
  -  preFixup = optionalString enableGTK3 /* gsettings schemas for file dialogues */ ''
  +  preFixup = optionalString enableGTK3 ''
       rm "$out/share/icons/hicolor/icon-theme.cache"
  -    wrapProgram "$out/bin/transmission-gtk" \
  -      --prefix XDG_DATA_DIRS : "$GSETTINGS_SCHEMAS_PATH"
     '';
   
     NIX_LDFLAGS = optionalString stdenv.isDarwin "-framework CoreFoundation";
  
positive.code: { stdenv, fetchurl, pkgconfig, intltool, file, makeWrapper
  , openssl, curl, libevent, inotify-tools, systemd, zlib
  , enableGTK3 ? false, gtk3
  , enableSystemd ? stdenv.isLinux
  
negative.code:     sha256 = "0pykmhi7pdmzq47glbj8i2im6iarp4wnj4l1pyvsrnba61f0939s";
    };
  
    nativeBuildInputs = [ pkgconfig ]
      ++ optionals enableGTK3 [ wrapGAppsHook ];
    buildInputs = [ intltool file openssl curl libevent zlib ]
      ++ optionals enableGTK3 [ gtk3 ]
      ++ optionals enableSystemd [ systemd ]
      ++ optionals stdenv.isLinux [ inotify-tools ];
  
  