anchor.diff:      rest
       pango
       telepathy_glib
  +    vala
       webkitgtk
       xorg.libX11
     ];
   
     configureFlags = [
       "--disable-maintainer-mode"
  +    "--disable-debug"
       "--enable-schemas-compile"
       "--enable-compile-warnings"
       "--disable-iso-c"
  
positive.code:     "--disable-gtk-doc-html"
      "--disable-gtk-doc-pdf"
      (enFlag "introspection" (gobject-introspection != null) null)
      "--enable-backend"
      "--disable-inspector"
      "--enable-exchange"
  
negative.code:     "--enable-owncloud"
      "--enable-facebook"
      "--enable-windows-live"
      "--enable-pocket"
      "--enable-kerberos"
      "--enable-lastfm"
  