Log Message:
Update to 2.18.3:

In Lablgtk-2.18.3:

2014.10.06 [Jacques]
  * add Gdk.Window.create_foreign and set_transient_for functions (Tim Cuthbertson)

2014.09.20 [Jacques]
  * CAMLparam initializes with Val_unit rather than 0 since ocaml 4.02.
    Fix a related problem in ml_gobject.
    This caused random crashes with unison (Christopher Zimmermann, PR#1425)
  * Also factorize some code to use Val_option_*
  * Replace XID by GdkNativeWindow where required.
    You may need to insert calls to Gdk.Window.native_of_xid in some places.