I'm looking for a way to determine how to know whether an application is using the GPU with Objective-C. I want to be able to determine if any applications currently running on the system have work going on on the GPU (ie: a reason why the latest MacBook Pros would switch to the discrete graphics over the Intel HD graphics).
I've tried getting the information by crossing the list of active windows with the list of windows that have their backing location stored in video memory using Quartz Window Services, but all that does is return the Dock application and I have other applications open that I know are using the GPU (Photoshop CS5, Interface Builder), that and the Dock doesn't require the 330m.