This works great when quitting and reopening the app,
but when closing a window and the reopening from Recent Files,
the current page isn't restored. In Preview.app, it is.
In the end, apparently I had "Close windows when quitting an
application" enabled in Desktop & Dock in System Settings. With that
turned off, it just worked (...but I still need to serialize the current
page in the view).
Even with it turned off, cmd-opt-q would "Quit and Keep Windows",
so I could've also used that for testing.
Automatic termination means that the app no longer shows up as
opened in the doc when the last Window is closed, but it's actually
still running and opens immediately when clicked again.
Sudden termination means that the app can close quickly on logout.
I think it means the runtime just calls _exit() and assumes all
data is saved continuously.
