Earlier quoted context omitted.
There's already a similar mechanism in the URL handlers, but Apple don't let you choose which application to use if multiple ones are registered. This still bugs me. I'd also like widgets one day.
> There's already a similar mechanism in the URL handlers, but Apple don't let you choose which application to use if multiple ones are registered. It also doesn't let you override core applications (in that it picks the first one either way), and last time I checked it if two applications registered the same handler and you removed the first one, the association didn't switch to the second one it just broke. May hav…
Hence "Apple don't let you choose which application to use" - it all happens at Apple's whim, and currently that excludes replacing system apps.