The ScreenManager keeps a list of secondary outputs, each with its own
swapchain, recreated after a lost device. Platform code adds, resizes and
removes them from any thread through Native_AddOutput() and friends, which
take effect at the start of the next frame.
Each frame, every output is drawn by the topmost screen that claims it
(Screen::renderOutput). EmuScreen claims Game outputs: it presents the
game there, laid out for that output, and leaves it out of the backbuffer,
where the touch controls and the menus stay. Not in non-buffered mode,
which draws straight into the backbuffer.
--game-window opens such an output on Mac, with Metal. It's a smoke test
for multiple swapchains, and a stand-in for an AirPlay display.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
