Why would I ever want to subject Mac users to GTK+???

The choice to use GTK+ (either through CoreGTK or any other way) on any platform is up to you. However if your program is written following a decent MVC pattern it should be relatively straight forward to port it to a new platform simply by re-writing the GUI portion. For instance if you had a program for the Mac written in Cocoa that you wanted to port to Linux you could use CoreGTK to make the GUI transition easier.

When will CoreGTK support GTK+ 3.x?

If a particular release does not yet exist we would love to have you help fill the gap by committing code 🙂

Does CoreGTK still support GTK+ 2.x?

No, this version is no longer supported but you can still download the old release if you really want to.

Does CoreGTK support Automatic Reference Counting (ARC)?

Currently CoreGTK does not support ARC. This is mainly due to issues in the gcc runtime but it wouldn’t take much to make CoreGTK support ARC if you want to give it a shot.