The dream now turns its window down to the same near-zero brightness as
the in-app screen saver, not just to the system's dim level, and builds
its ComposeView from the window's context rather than the service's.
The in-app screen saver finishes once it is no longer shown, so waking
the phone shows the lock screen, and rotating it into a stand no longer
recreates it. The outgoing minute of the crossfade is hidden from screen
readers.