Here's my prediction.
I think when you press the red cross now it will actually close the application fully. Then when you click it on the dock again it will open instantly from the "autosave" it took when you closed the app so it will be like you never closed it but it wouldn't hog resources in the background.
Something like that... That way you don't even need the lights.
I hope not. I like being able to close the iTunes window and still have the music play. "Minimizing" is stupid; closing the window, not the app, is far better.