Can GTK fill the needs of stdgui?

Can GTK+ meet the primary goals of stdgui?

1. Programming language independent?
No.  It's a huge C API.  The latest Glade GUI builder generates mostly language agnostic XML, however, like wxWidgets' XRC, it's still tightly coupled to the toolkit and thus would be rather hard to run on top of anything else.

2. Native rendering?
Limited  (according to this stackoverflow reply).  There is however some ongoing work to make a native OSX/Cocoa port.  (Aside: while searching this topic I noticed that the Tk toolkit has a Cocoa port)

3. Rapid Development?
Yes.  With a GUI builder like Glade.

Summary
Not what I'm looking for.  Like Qt, GTK is built to be a stand-alone toolkit, with a big API.