Function run_app_on 

pub fn run_app_on<P, A>(
    config: WindowConfig,
    terminal: Terminal<WindowBackend<P>>,
    app: A,
) -> Result<(), EventLoopError>
where
    P: Presenter + 'static,
    A: App<WindowBackend<P>> + 'static,

Same as run_app, but takes an already-built Terminal instead of a bare presenter.

run_app builds its Terminal internally (Terminal::new(WindowBackend::new(presenter))); this is the lower-level entry for a caller that needs to configure the Terminal (or reach into its WindowBackend) before the loop starts, which is impossible through run_app alone.

See run_app’s “Resizing applies before update runs” and “Return contract differs on wasm32” sections, and https://main.retroglyph.dev/book/explanation/architecture.html#presenting-is-automatic: this function shares all three behaviors.

Errors

Returns EventLoopError if the event loop cannot be created or fails while running.