currently the design is copied directly from aleph BEES. each grid app object responds to the message ‘focus’ by ‘grabbing’ focus from a central controller. This is an excellent design on the aleph because you have patchable buttons on the front panel which can handle the focus-swapping. In my pd external, apps respond to ‘unfocus’ by telling the central controller to focus, which currently just displays a pattern.
Haven’t yet implemented a navigation page in the central controller, partly because at the back of my mind I was thinking it’d be cool if such a thing was not constrained to my pd ops…