What a launch's burst is written with, handed to the declaration's burst
by the entry on every launch:
firstScreen is the mark of the place in the burst where the first screen
enters through the launch edge (enterRoot) and sends its own enter,
which yields the screen's navigate. The burst runs it exactly once, at
the position the recording shows; never or twice is
ScreenLaunchFirstScreenError.
What a launch's burst is written with, handed to the declaration's
burstby the entry on every launch:firstScreenis the mark of the place in the burst where the first screen enters through the launch edge (enterRoot) and sends its ownenter, which yields the screen'snavigate. The burst runs it exactly once, at the position the recording shows; never or twice is ScreenLaunchFirstScreenError.inputis the caller's launch input.