pcmanfm: build with gtk3

pkgs/development/libraries/libfm/default.nix

@@ -1,6 +1,8 @@
-{ stdenv, fetchurl, glib, gtk2, intltool, menu-cache, pango, pkgconfig, vala_0_34
-, extraOnly ? false }:
+{ stdenv, fetchurl, glib, intltool, menu-cache, pango, pkgconfig, vala_0_34
+, extraOnly ? false
+, withGtk3 ? false, gtk2, gtk3 }:
 let
+    gtk = if withGtk3 then gtk3 else gtk2;
     inherit (stdenv.lib) optional;
 in
 stdenv.mkDerivation rec {
@@ -14,10 +16,13 @@ stdenv.mkDerivation rec {
     sha256 = "0nlvfwh09gbq8bkbvwnw6iqr918rrs9gc9ljb9pjspyg408bn1n7";
   };
 
-  buildInputs = [ glib gtk2 intltool pango pkgconfig vala_0_34 ]
+  buildInputs = [ glib gtk intltool pango pkgconfig vala_0_34 ]
                 ++ optional (!extraOnly) menu-cache;
 
-  configureFlags = optional extraOnly "--with-extra-only";
+  configureFlags = [ (optional extraOnly "--with-extra-only")
+                     (optional withGtk3 "--with-gtk=3") ];
+
+  enableParallelBuilding = true;
 
   meta = with stdenv.lib; {
     homepage = http://blog.lxde.org/?cat=28/;