15-inch Mid 2010 MacBook Pro, OS X 10.10.3, latest version of gfxCardStatus
If I choose "Integrated Only," sometimes the system (presumably) switches to the discrete GPU on its own. When that happens, the gfxCardStatus menu bar indicator shows "Discrete Only." I can switch back to Integrated Only manually unless some program is running that prevents it.
15-inch Mid 2010 MacBook Pro, OS X 10.10.3, latest version of gfxCardStatus
If I choose "Integrated Only," sometimes the system (presumably) switches to the discrete GPU on its own. When that happens, the gfxCardStatus menu bar indicator shows "Discrete Only." I can switch back to Integrated Only manually unless some program is running that prevents it.