Code to support it was lying around for long already, but not controlled by UI nicely. Now you have in user preferences "System" tab an option to set it. NOTE: - it only works saving as User startup.blend, and restart Blender. - your system should support it, no check for it is visible in UI - tested only on iMac OSX 10.7 Screenshot: http://www.blender.org/bf/chinchilla.blend.png