[GUI] Integrating a GTK application into OS X

[scl <scl gplus gmail com>]

Hi,

I'm developing in the GIMP project and am currently
improving its integration into the OS X look and
feel. As we are using GTK 2 I don't think we can use
GTK's built-in OS X integration (in GTK+ 3.4).
With respect to
https://wiki.gnome.org/Projects/GTK+/OSX/Integration
I'm improving an existing GTK+ 2 theme.

While the natural goal is the tight integration into
the OS X look and feel I'm on the other hand hesitating
how close to the original such a theme can be to not
infringe Apple's interests (see the Apple-vs.-Microsoft
lawsuit years ago and the related PearOS story lately).
From my point of view using the GTK-Quartz-Engine
could solve it if it used the Cocoa framework instead
of the outdated Carbon framework.
Are there any experiences, best practices or guidelines
to solve this integration problem?
John, have you planned to update the GTK Quartz Engine
soon?

Thank you in advance,

Sven