missing symbols when gtk is built with Quartz backend

[guest]

On OS X, if using the quartz backend (http://gtk-osx.sourceforge.net/), gtk2hs will build but any programs built with it fail with the message:

Undefined symbols:
  "_gdk_x11_drawable_get_xid", referenced from:
      _s1Spk_info in libHSgtk-0.11.2.a(Structs.o)
ld: symbol(s) not found
collect2: ld returned 1 exit status

The problem seems to be the function "drawableGetID" defined in Graphics/UI/Gtk/General/Structs.hsc. This function calls

#if !defined(WIN32)
     withForeignPtr drawable gdk_x11_drawable_get_xid
#else
     withForeignPtr drawable gdk_win32_drawable_get_handle
#endif

but gdk_x11_drawable_get_xid is not exported from the Quartz backend. Of course gdk_win32_drawable_get_handle isn't available either.

I don't know which function is the correct replacement on Quartz, but just leaving it out allows programs to link and appear to run properly.