Introduce `daemon` API and unify shell runtimes

8 files changed, 253 insertions, 1522 deletions

diff --git a/winit/src/application.rs b/winit/src/application.rs
deleted file mode 100644
index a93878ea..00000000
--- a/winit/src/application.rs
+++ /dev/null
@@ -1,1082 +0,0 @@
-//! Create interactive, native cross-platform applications.
-mod state;
-
-pub use state::State;
-
-use crate::conversion;
-use crate::core;
-use crate::core::mouse;
-use crate::core::renderer;
-use crate::core::time::Instant;
-use crate::core::widget::operation;
-use crate::core::window;
-use crate::core::{Color, Event, Point, Size, Theme};
-use crate::futures::futures;
-use crate::futures::subscription::{self, Subscription};
-use crate::futures::{Executor, Runtime};
-use crate::graphics;
-use crate::graphics::compositor::{self, Compositor};
-use crate::runtime::clipboard;
-use crate::runtime::program::Program;
-use crate::runtime::user_interface::{self, UserInterface};
-use crate::runtime::{Action, Debug, Task};
-use crate::{Clipboard, Error, Proxy, Settings};
-
-use futures::channel::mpsc;
-use futures::channel::oneshot;
-
-use std::borrow::Cow;
-use std::mem::ManuallyDrop;
-use std::sync::Arc;
-
-/// An interactive, native cross-platform application.
-///
-/// This trait is the main entrypoint of Iced. Once implemented, you can run
-/// your GUI application by simply calling [`run`]. It will run in
-/// its own window.
-///
-/// An [`Application`] can execute asynchronous actions by returning a
-/// [`Task`] in some of its methods.
-///
-/// When using an [`Application`] with the `debug` feature enabled, a debug view
-/// can be toggled by pressing `F12`.
-pub trait Application: Program
-where
-    Self::Theme: DefaultStyle,
-{
-    /// The data needed to initialize your [`Application`].
-    type Flags;
-
-    /// Initializes the [`Application`] with the flags provided to
-    /// [`run`] as part of the [`Settings`].
-    ///
-    /// Here is where you should return the initial state of your app.
-    ///
-    /// Additionally, you can return a [`Task`] if you need to perform some
-    /// async action in the background on startup. This is useful if you want to
-    /// load state from a file, perform an initial HTTP request, etc.
-    fn new(flags: Self::Flags) -> (Self, Task<Self::Message>);
-
-    /// Returns the current title of the [`Application`].
-    ///
-    /// This title can be dynamic! The runtime will automatically update the
-    /// title of your application when necessary.
-    fn title(&self) -> String;
-
-    /// Returns the current `Theme` of the [`Application`].
-    fn theme(&self) -> Self::Theme;
-
-    /// Returns the `Style` variation of the `Theme`.
-    fn style(&self, theme: &Self::Theme) -> Appearance {
-        theme.default_style()
-    }
-
-    /// Returns the event `Subscription` for the current state of the
-    /// application.
-    ///
-    /// The messages produced by the `Subscription` will be handled by
-    /// [`update`](#tymethod.update).
-    ///
-    /// A `Subscription` will be kept alive as long as you keep returning it!
-    ///
-    /// By default, it returns an empty subscription.
-    fn subscription(&self) -> Subscription<Self::Message> {
-        Subscription::none()
-    }
-
-    /// Returns the scale factor of the [`Application`].
-    ///
-    /// It can be used to dynamically control the size of the UI at runtime
-    /// (i.e. zooming).
-    ///
-    /// For instance, a scale factor of `2.0` will make widgets twice as big,
-    /// while a scale factor of `0.5` will shrink them to half their size.
-    ///
-    /// By default, it returns `1.0`.
-    fn scale_factor(&self) -> f64 {
-        1.0
-    }
-}
-
-/// The appearance of an application.
-#[derive(Debug, Clone, Copy, PartialEq)]
-pub struct Appearance {
-    /// The background [`Color`] of the application.
-    pub background_color: Color,
-
-    /// The default text [`Color`] of the application.
-    pub text_color: Color,
-}
-
-/// The default style of an [`Application`].
-pub trait DefaultStyle {
-    /// Returns the default style of an [`Application`].
-    fn default_style(&self) -> Appearance;
-}
-
-impl DefaultStyle for Theme {
-    fn default_style(&self) -> Appearance {
-        default(self)
-    }
-}
-
-/// The default [`Appearance`] of an [`Application`] with the built-in [`Theme`].
-pub fn default(theme: &Theme) -> Appearance {
-    let palette = theme.extended_palette();
-
-    Appearance {
-        background_color: palette.background.base.color,
-        text_color: palette.background.base.text,
-    }
-}
-
-/// Runs an [`Application`] with an executor, compositor, and the provided
-/// settings.
-pub fn run<A, E, C>(
-    settings: Settings<A::Flags>,
-    graphics_settings: graphics::Settings,
-) -> Result<(), Error>
-where
-    A: Application + 'static,
-    E: Executor + 'static,
-    C: Compositor<Renderer = A::Renderer> + 'static,
-    A::Theme: DefaultStyle,
-{
-    use futures::task;
-    use futures::Future;
-    use winit::event_loop::EventLoop;
-
-    let mut debug = Debug::new();
-    debug.startup_started();
-
-    let event_loop = EventLoop::with_user_event()
-        .build()
-        .expect("Create event loop");
-
-    let (proxy, worker) = Proxy::new(event_loop.create_proxy());
-
-    let mut runtime = {
-        let executor = E::new().map_err(Error::ExecutorCreationFailed)?;
-        executor.spawn(worker);
-
-        Runtime::new(executor, proxy.clone())
-    };
-
-    let (application, task) = {
-        let flags = settings.flags;
-
-        runtime.enter(|| A::new(flags))
-    };
-
-    if let Some(stream) = task.into_stream() {
-        runtime.run(stream);
-    }
-
-    let id = settings.id;
-    let title = application.title();
-
-    let (boot_sender, boot_receiver) = oneshot::channel();
-    let (event_sender, event_receiver) = mpsc::unbounded();
-    let (control_sender, control_receiver) = mpsc::unbounded();
-
-    let instance = Box::pin(run_instance::<A, E, C>(
-        application,
-        runtime,
-        proxy,
-        debug,
-        boot_receiver,
-        event_receiver,
-        control_sender,
-        settings.fonts,
-    ));
-
-    let context = task::Context::from_waker(task::noop_waker_ref());
-
-    struct Runner<Message: 'static, F, C> {
-        instance: std::pin::Pin<Box<F>>,
-        context: task::Context<'static>,
-        boot: Option<BootConfig<C>>,
-        sender: mpsc::UnboundedSender<winit::event::Event<Action<Message>>>,
-        receiver: mpsc::UnboundedReceiver<winit::event_loop::ControlFlow>,
-        error: Option<Error>,
-        #[cfg(target_arch = "wasm32")]
-        is_booted: std::rc::Rc<std::cell::RefCell<bool>>,
-        #[cfg(target_arch = "wasm32")]
-        queued_events: Vec<winit::event::Event<Action<Message>>>,
-    }
-
-    struct BootConfig<C> {
-        sender: oneshot::Sender<Boot<C>>,
-        id: Option<String>,
-        title: String,
-        window_settings: window::Settings,
-        graphics_settings: graphics::Settings,
-    }
-
-    let runner = Runner {
-        instance,
-        context,
-        boot: Some(BootConfig {
-            sender: boot_sender,
-            id,
-            title,
-            window_settings: settings.window,
-            graphics_settings,
-        }),
-        sender: event_sender,
-        receiver: control_receiver,
-        error: None,
-        #[cfg(target_arch = "wasm32")]
-        is_booted: std::rc::Rc::new(std::cell::RefCell::new(false)),
-        #[cfg(target_arch = "wasm32")]
-        queued_events: Vec::new(),
-    };
-
-    impl<Message, F, C> winit::application::ApplicationHandler<Action<Message>>
-        for Runner<Message, F, C>
-    where
-        F: Future<Output = ()>,
-        C: Compositor + 'static,
-    {
-        fn resumed(&mut self, event_loop: &winit::event_loop::ActiveEventLoop) {
-            let Some(BootConfig {
-                sender,
-                id,
-                title,
-                window_settings,
-                graphics_settings,
-            }) = self.boot.take()
-            else {
-                return;
-            };
-
-            let should_be_visible = window_settings.visible;
-            let exit_on_close_request = window_settings.exit_on_close_request;
-
-            #[cfg(target_arch = "wasm32")]
-            let target = window_settings.platform_specific.target.clone();
-
-            let window_attributes = conversion::window_attributes(
-                window_settings,
-                &title,
-                event_loop.primary_monitor(),
-                id,
-            )
-            .with_visible(false);
-
-            log::debug!("Window attributes: {window_attributes:#?}");
-
-            let window = match event_loop.create_window(window_attributes) {
-                Ok(window) => Arc::new(window),
-                Err(error) => {
-                    self.error = Some(Error::WindowCreationFailed(error));
-                    event_loop.exit();
-                    return;
-                }
-            };
-
-            let finish_boot = {
-                let window = window.clone();
-
-                async move {
-                    let compositor =
-                        C::new(graphics_settings, window.clone()).await?;
-
-                    sender
-                        .send(Boot {
-                            window,
-                            compositor,
-                            should_be_visible,
-                            exit_on_close_request,
-                        })
-                        .ok()
-                        .expect("Send boot event");
-
-                    Ok::<_, graphics::Error>(())
-                }
-            };
-
-            #[cfg(not(target_arch = "wasm32"))]
-            if let Err(error) = futures::executor::block_on(finish_boot) {
-                self.error = Some(Error::GraphicsCreationFailed(error));
-                event_loop.exit();
-            }
-
-            #[cfg(target_arch = "wasm32")]
-            {
-                use winit::platform::web::WindowExtWebSys;
-
-                let canvas = window.canvas().expect("Get window canvas");
-                let _ = canvas.set_attribute(
-                    "style",
-                    "display: block; width: 100%; height: 100%",
-                );
-
-                let window = web_sys::window().unwrap();
-                let document = window.document().unwrap();
-                let body = document.body().unwrap();
-
-                let target = target.and_then(|target| {
-                    body.query_selector(&format!("#{target}"))
-                        .ok()
-                        .unwrap_or(None)
-                });
-
-                match target {
-                    Some(node) => {
-                        let _ = node.replace_with_with_node_1(&canvas).expect(
-                            &format!("Could not replace #{}", node.id()),
-                        );
-                    }
-                    None => {
-                        let _ = body
-                            .append_child(&canvas)
-                            .expect("Append canvas to HTML body");
-                    }
-                };
-
-                let is_booted = self.is_booted.clone();
-
-                wasm_bindgen_futures::spawn_local(async move {
-                    finish_boot.await.expect("Finish boot!");
-
-                    *is_booted.borrow_mut() = true;
-                });
-            }
-        }
-
-        fn new_events(
-            &mut self,
-            event_loop: &winit::event_loop::ActiveEventLoop,
-            cause: winit::event::StartCause,
-        ) {
-            if self.boot.is_some() {
-                return;
-            }
-
-            self.process_event(
-                event_loop,
-                winit::event::Event::NewEvents(cause),
-            );
-        }
-
-        fn window_event(
-            &mut self,
-            event_loop: &winit::event_loop::ActiveEventLoop,
-            window_id: winit::window::WindowId,
-            event: winit::event::WindowEvent,
-        ) {
-            #[cfg(target_os = "windows")]
-            let is_move_or_resize = matches!(
-                event,
-                winit::event::WindowEvent::Resized(_)
-                    | winit::event::WindowEvent::Moved(_)
-            );
-
-            self.process_event(
-                event_loop,
-                winit::event::Event::WindowEvent { window_id, event },
-            );
-
-            // TODO: Remove when unnecessary
-            // On Windows, we emulate an `AboutToWait` event after every `Resized` event
-            // since the event loop does not resume during resize interaction.
-            // More details: https://github.com/rust-windowing/winit/issues/3272
-            #[cfg(target_os = "windows")]
-            {
-                if is_move_or_resize {
-                    self.process_event(
-                        event_loop,
-                        winit::event::Event::AboutToWait,
-                    );
-                }
-            }
-        }
-
-        fn user_event(
-            &mut self,
-            event_loop: &winit::event_loop::ActiveEventLoop,
-            action: Action<Message>,
-        ) {
-            self.process_event(
-                event_loop,
-                winit::event::Event::UserEvent(action),
-            );
-        }
-
-        fn about_to_wait(
-            &mut self,
-            event_loop: &winit::event_loop::ActiveEventLoop,
-        ) {
-            self.process_event(event_loop, winit::event::Event::AboutToWait);
-        }
-    }
-
-    impl<Message, F, C> Runner<Message, F, C>
-    where
-        F: Future<Output = ()>,
-    {
-        fn process_event(
-            &mut self,
-            event_loop: &winit::event_loop::ActiveEventLoop,
-            event: winit::event::Event<Action<Message>>,
-        ) {
-            // On Wasm, events may start being processed before the compositor
-            // boots up. We simply queue them and process them once ready.
-            #[cfg(target_arch = "wasm32")]
-            if !*self.is_booted.borrow() {
-                self.queued_events.push(event);
-                return;
-            } else if !self.queued_events.is_empty() {
-                let queued_events = std::mem::take(&mut self.queued_events);
-
-                // This won't infinitely recurse, since we `mem::take`
-                for event in queued_events {
-                    self.process_event(event_loop, event);
-                }
-            }
-
-            if event_loop.exiting() {
-                return;
-            }
-
-            self.sender.start_send(event).expect("Send event");
-
-            let poll = self.instance.as_mut().poll(&mut self.context);
-
-            match poll {
-                task::Poll::Pending => {
-                    if let Ok(Some(flow)) = self.receiver.try_next() {
-                        event_loop.set_control_flow(flow);
-                    }
-                }
-                task::Poll::Ready(_) => {
-                    event_loop.exit();
-                }
-            }
-        }
-    }
-
-    #[cfg(not(target_arch = "wasm32"))]
-    {
-        let mut runner = runner;
-        let _ = event_loop.run_app(&mut runner);
-
-        runner.error.map(Err).unwrap_or(Ok(()))
-    }
-
-    #[cfg(target_arch = "wasm32")]
-    {
-        use winit::platform::web::EventLoopExtWebSys;
-        let _ = event_loop.spawn_app(runner);
-
-        Ok(())
-    }
-}
-
-struct Boot<C> {
-    window: Arc<winit::window::Window>,
-    compositor: C,
-    should_be_visible: bool,
-    exit_on_close_request: bool,
-}
-
-async fn run_instance<A, E, C>(
-    mut application: A,
-    mut runtime: Runtime<E, Proxy<A::Message>, Action<A::Message>>,
-    mut proxy: Proxy<A::Message>,
-    mut debug: Debug,
-    mut boot: oneshot::Receiver<Boot<C>>,
-    mut event_receiver: mpsc::UnboundedReceiver<
-        winit::event::Event<Action<A::Message>>,
-    >,
-    mut control_sender: mpsc::UnboundedSender<winit::event_loop::ControlFlow>,
-    fonts: Vec<Cow<'static, [u8]>>,
-) where
-    A: Application + 'static,
-    E: Executor + 'static,
-    C: Compositor<Renderer = A::Renderer> + 'static,
-    A::Theme: DefaultStyle,
-{
-    use futures::stream::StreamExt;
-    use winit::event;
-    use winit::event_loop::ControlFlow;
-
-    let Boot {
-        window,
-        mut compositor,
-        should_be_visible,
-        exit_on_close_request,
-    } = boot.try_recv().ok().flatten().expect("Receive boot");
-
-    let mut renderer = compositor.create_renderer();
-
-    for font in fonts {
-        compositor.load_font(font);
-    }
-
-    let mut state = State::new(&application, &window);
-    let mut viewport_version = state.viewport_version();
-    let physical_size = state.physical_size();
-
-    let mut clipboard = Clipboard::connect(&window);
-    let cache = user_interface::Cache::default();
-    let mut surface = compositor.create_surface(
-        window.clone(),
-        physical_size.width,
-        physical_size.height,
-    );
-    let mut should_exit = false;
-
-    if should_be_visible {
-        window.set_visible(true);
-    }
-
-    runtime.track(
-        application
-            .subscription()
-            .map(Action::Output)
-            .into_recipes(),
-    );
-
-    let mut user_interface = ManuallyDrop::new(build_user_interface(
-        &application,
-        cache,
-        &mut renderer,
-        state.logical_size(),
-        &mut debug,
-    ));
-
-    let mut mouse_interaction = mouse::Interaction::default();
-    let mut events = Vec::new();
-    let mut messages = Vec::new();
-    let mut user_events = 0;
-    let mut redraw_pending = false;
-
-    debug.startup_finished();
-
-    while let Some(event) = event_receiver.next().await {
-        match event {
-            event::Event::NewEvents(
-                event::StartCause::Init
-                | event::StartCause::ResumeTimeReached { .. },
-            ) if !redraw_pending => {
-                window.request_redraw();
-                redraw_pending = true;
-            }
-            event::Event::PlatformSpecific(event::PlatformSpecific::MacOS(
-                event::MacOS::ReceivedUrl(url),
-            )) => {
-                runtime.broadcast(subscription::Event::PlatformSpecific(
-                    subscription::PlatformSpecific::MacOS(
-                        subscription::MacOS::ReceivedUrl(url),
-                    ),
-                ));
-            }
-            event::Event::UserEvent(action) => {
-                run_action(
-                    action,
-                    &mut user_interface,
-                    &mut compositor,
-                    &mut surface,
-                    &state,
-                    &mut renderer,
-                    &mut messages,
-                    &mut clipboard,
-                    &mut should_exit,
-                    &mut debug,
-                    &window,
-                );
-
-                user_events += 1;
-            }
-            event::Event::WindowEvent {
-                event: event::WindowEvent::RedrawRequested { .. },
-                ..
-            } => {
-                let physical_size = state.physical_size();
-
-                if physical_size.width == 0 || physical_size.height == 0 {
-                    continue;
-                }
-
-                let current_viewport_version = state.viewport_version();
-
-                if viewport_version != current_viewport_version {
-                    let logical_size = state.logical_size();
-
-                    debug.layout_started();
-                    user_interface = ManuallyDrop::new(
-                        ManuallyDrop::into_inner(user_interface)
-                            .relayout(logical_size, &mut renderer),
-                    );
-                    debug.layout_finished();
-
-                    compositor.configure_surface(
-                        &mut surface,
-                        physical_size.width,
-                        physical_size.height,
-                    );
-
-                    viewport_version = current_viewport_version;
-                }
-
-                // TODO: Avoid redrawing all the time by forcing widgets to
-                // request redraws on state changes
-                //
-                // Then, we can use the `interface_state` here to decide if a redraw
-                // is needed right away, or simply wait until a specific time.
-                let redraw_event = Event::Window(
-                    window::Event::RedrawRequested(Instant::now()),
-                );
-
-                let (interface_state, _) = user_interface.update(
-                    &[redraw_event.clone()],
-                    state.cursor(),
-                    &mut renderer,
-                    &mut clipboard,
-                    &mut messages,
-                );
-
-                let _ = control_sender.start_send(match interface_state {
-                    user_interface::State::Updated {
-                        redraw_request: Some(redraw_request),
-                    } => match redraw_request {
-                        window::RedrawRequest::NextFrame => {
-                            window.request_redraw();
-
-                            ControlFlow::Wait
-                        }
-                        window::RedrawRequest::At(at) => {
-                            ControlFlow::WaitUntil(at)
-                        }
-                    },
-                    _ => ControlFlow::Wait,
-                });
-
-                runtime.broadcast(subscription::Event::Interaction {
-                    window: window::Id::MAIN,
-                    event: redraw_event,
-                    status: core::event::Status::Ignored,
-                });
-
-                debug.draw_started();
-                let new_mouse_interaction = user_interface.draw(
-                    &mut renderer,
-                    state.theme(),
-                    &renderer::Style {
-                        text_color: state.text_color(),
-                    },
-                    state.cursor(),
-                );
-                redraw_pending = false;
-                debug.draw_finished();
-
-                if new_mouse_interaction != mouse_interaction {
-                    window.set_cursor(conversion::mouse_interaction(
-                        new_mouse_interaction,
-                    ));
-
-                    mouse_interaction = new_mouse_interaction;
-                }
-
-                debug.render_started();
-                match compositor.present(
-                    &mut renderer,
-                    &mut surface,
-                    state.viewport(),
-                    state.background_color(),
-                    &debug.overlay(),
-                ) {
-                    Ok(()) => {
-                        debug.render_finished();
-
-                        // TODO: Handle animations!
-                        // Maybe we can use `ControlFlow::WaitUntil` for this.
-                    }
-                    Err(error) => match error {
-                        // This is an unrecoverable error.
-                        compositor::SurfaceError::OutOfMemory => {
-                            panic!("{error:?}");
-                        }
-                        _ => {
-                            debug.render_finished();
-
-                            // Try rendering again next frame.
-                            window.request_redraw();
-                        }
-                    },
-                }
-            }
-            event::Event::WindowEvent {
-                event: window_event,
-                ..
-            } => {
-                if requests_exit(&window_event, state.modifiers())
-                    && exit_on_close_request
-                {
-                    break;
-                }
-
-                state.update(&window, &window_event, &mut debug);
-
-                if let Some(event) = conversion::window_event(
-                    window_event,
-                    state.scale_factor(),
-                    state.modifiers(),
-                ) {
-                    events.push(event);
-                }
-            }
-            event::Event::AboutToWait => {
-                if events.is_empty() && messages.is_empty() {
-                    continue;
-                }
-
-                debug.event_processing_started();
-
-                let (interface_state, statuses) = user_interface.update(
-                    &events,
-                    state.cursor(),
-                    &mut renderer,
-                    &mut clipboard,
-                    &mut messages,
-                );
-
-                debug.event_processing_finished();
-
-                for (event, status) in
-                    events.drain(..).zip(statuses.into_iter())
-                {
-                    runtime.broadcast(subscription::Event::Interaction {
-                        window: window::Id::MAIN,
-                        event,
-                        status,
-                    });
-                }
-
-                if !messages.is_empty()
-                    || matches!(
-                        interface_state,
-                        user_interface::State::Outdated
-                    )
-                {
-                    let cache =
-                        ManuallyDrop::into_inner(user_interface).into_cache();
-
-                    // Update application
-                    update(
-                        &mut application,
-                        &mut state,
-                        &mut runtime,
-                        &mut debug,
-                        &mut messages,
-                        &window,
-                    );
-
-                    user_interface = ManuallyDrop::new(build_user_interface(
-                        &application,
-                        cache,
-                        &mut renderer,
-                        state.logical_size(),
-                        &mut debug,
-                    ));
-
-                    if should_exit {
-                        break;
-                    }
-
-                    if user_events > 0 {
-                        proxy.free_slots(user_events);
-                        user_events = 0;
-                    }
-                }
-
-                if !redraw_pending {
-                    window.request_redraw();
-                    redraw_pending = true;
-                }
-            }
-            _ => {}
-        }
-    }
-
-    // Manually drop the user interface
-    drop(ManuallyDrop::into_inner(user_interface));
-}
-
-/// Returns true if the provided event should cause an [`Application`] to
-/// exit.
-pub fn requests_exit(
-    event: &winit::event::WindowEvent,
-    _modifiers: winit::keyboard::ModifiersState,
-) -> bool {
-    use winit::event::WindowEvent;
-
-    match event {
-        WindowEvent::CloseRequested => true,
-        #[cfg(target_os = "macos")]
-        WindowEvent::KeyboardInput {
-            event:
-                winit::event::KeyEvent {
-                    logical_key: winit::keyboard::Key::Character(c),
-                    state: winit::event::ElementState::Pressed,
-                    ..
-                },
-            ..
-        } if c == "q" && _modifiers.super_key() => true,
-        _ => false,
-    }
-}
-
-/// Builds a [`UserInterface`] for the provided [`Application`], logging
-/// [`struct@Debug`] information accordingly.
-pub fn build_user_interface<'a, A: Application>(
-    application: &'a A,
-    cache: user_interface::Cache,
-    renderer: &mut A::Renderer,
-    size: Size,
-    debug: &mut Debug,
-) -> UserInterface<'a, A::Message, A::Theme, A::Renderer>
-where
-    A::Theme: DefaultStyle,
-{
-    debug.view_started();
-    let view = application.view();
-    debug.view_finished();
-
-    debug.layout_started();
-    let user_interface = UserInterface::build(view, size, cache, renderer);
-    debug.layout_finished();
-
-    user_interface
-}
-
-/// Updates an [`Application`] by feeding it the provided messages, spawning any
-/// resulting [`Task`], and tracking its [`Subscription`].
-pub fn update<A: Application, E: Executor>(
-    application: &mut A,
-    state: &mut State<A>,
-    runtime: &mut Runtime<E, Proxy<A::Message>, Action<A::Message>>,
-    debug: &mut Debug,
-    messages: &mut Vec<A::Message>,
-    window: &winit::window::Window,
-) where
-    A::Theme: DefaultStyle,
-{
-    for message in messages.drain(..) {
-        debug.log_message(&message);
-
-        debug.update_started();
-        let task = runtime.enter(|| application.update(message));
-        debug.update_finished();
-
-        if let Some(stream) = task.into_stream() {
-            runtime.run(stream);
-        }
-    }
-
-    state.synchronize(application, window);
-
-    let subscription = application.subscription();
-    runtime.track(subscription.map(Action::Output).into_recipes());
-}
-
-/// Runs the actions of a [`Task`].
-pub fn run_action<A, C>(
-    action: Action<A::Message>,
-    user_interface: &mut UserInterface<'_, A::Message, A::Theme, C::Renderer>,
-    compositor: &mut C,
-    surface: &mut C::Surface,
-    state: &State<A>,
-    renderer: &mut A::Renderer,
-    messages: &mut Vec<A::Message>,
-    clipboard: &mut Clipboard,
-    should_exit: &mut bool,
-    debug: &mut Debug,
-    window: &winit::window::Window,
-) where
-    A: Application,
-    C: Compositor<Renderer = A::Renderer> + 'static,
-    A::Theme: DefaultStyle,
-{
-    use crate::runtime::system;
-    use crate::runtime::window;
-
-    match action {
-        Action::Clipboard(action) => match action {
-            clipboard::Action::Read { target, channel } => {
-                let _ = channel.send(clipboard.read(target));
-            }
-            clipboard::Action::Write { target, contents } => {
-                clipboard.write(target, contents);
-            }
-        },
-        Action::Window(action) => match action {
-            window::Action::Close(_id) => {
-                *should_exit = true;
-            }
-            window::Action::Drag(_id) => {
-                let _res = window.drag_window();
-            }
-            window::Action::Open { .. } => {
-                log::warn!(
-                    "Spawning a window is only available with \
-                        multi-window applications."
-                );
-            }
-            window::Action::Resize(_id, size) => {
-                let _ = window.request_inner_size(winit::dpi::LogicalSize {
-                    width: size.width,
-                    height: size.height,
-                });
-            }
-            window::Action::FetchSize(_id, channel) => {
-                let size =
-                    window.inner_size().to_logical(window.scale_factor());
-
-                let _ = channel.send(Size::new(size.width, size.height));
-            }
-            window::Action::FetchMaximized(_id, channel) => {
-                let _ = channel.send(window.is_maximized());
-            }
-            window::Action::Maximize(_id, maximized) => {
-                window.set_maximized(maximized);
-            }
-            window::Action::FetchMinimized(_id, channel) => {
-                let _ = channel.send(window.is_minimized());
-            }
-            window::Action::Minimize(_id, minimized) => {
-                window.set_minimized(minimized);
-            }
-            window::Action::FetchPosition(_id, channel) => {
-                let position = window
-                    .inner_position()
-                    .map(|position| {
-                        let position =
-                            position.to_logical::<f32>(window.scale_factor());
-
-                        Point::new(position.x, position.y)
-                    })
-                    .ok();
-
-                let _ = channel.send(position);
-            }
-            window::Action::Move(_id, position) => {
-                window.set_outer_position(winit::dpi::LogicalPosition {
-                    x: position.x,
-                    y: position.y,
-                });
-            }
-            window::Action::ChangeMode(_id, mode) => {
-                window.set_visible(conversion::visible(mode));
-                window.set_fullscreen(conversion::fullscreen(
-                    window.current_monitor(),
-                    mode,
-                ));
-            }
-            window::Action::ChangeIcon(_id, icon) => {
-                window.set_window_icon(conversion::icon(icon));
-            }
-            window::Action::FetchMode(_id, channel) => {
-                let mode = if window.is_visible().unwrap_or(true) {
-                    conversion::mode(window.fullscreen())
-                } else {
-                    core::window::Mode::Hidden
-                };
-
-                let _ = channel.send(mode);
-            }
-            window::Action::ToggleMaximize(_id) => {
-                window.set_maximized(!window.is_maximized());
-            }
-            window::Action::ToggleDecorations(_id) => {
-                window.set_decorations(!window.is_decorated());
-            }
-            window::Action::RequestUserAttention(_id, user_attention) => {
-                window.request_user_attention(
-                    user_attention.map(conversion::user_attention),
-                );
-            }
-            window::Action::GainFocus(_id) => {
-                window.focus_window();
-            }
-            window::Action::ChangeLevel(_id, level) => {
-                window.set_window_level(conversion::window_level(level));
-            }
-            window::Action::ShowSystemMenu(_id) => {
-                if let mouse::Cursor::Available(point) = state.cursor() {
-                    window.show_window_menu(winit::dpi::LogicalPosition {
-                        x: point.x,
-                        y: point.y,
-                    });
-                }
-            }
-            window::Action::FetchRawId(_id, channel) => {
-                let _ = channel.send(window.id().into());
-            }
-            window::Action::RunWithHandle(_id, f) => {
-                use window::raw_window_handle::HasWindowHandle;
-
-                if let Ok(handle) = window.window_handle() {
-                    f(handle);
-                }
-            }
-
-            window::Action::Screenshot(_id, channel) => {
-                let bytes = compositor.screenshot(
-                    renderer,
-                    surface,
-                    state.viewport(),
-                    state.background_color(),
-                    &debug.overlay(),
-                );
-
-                let _ = channel.send(window::Screenshot::new(
-                    bytes,
-                    state.physical_size(),
-                    state.viewport().scale_factor(),
-                ));
-            }
-        },
-        Action::System(action) => match action {
-            system::Action::QueryInformation(_channel) => {
-                #[cfg(feature = "system")]
-                {
-                    let graphics_info = compositor.fetch_information();
-
-                    let _ = std::thread::spawn(move || {
-                        let information =
-                            crate::system::information(graphics_info);
-
-                        let _ = _channel.send(information);
-                    });
-                }
-            }
-        },
-        Action::Widget(operation) => {
-            let mut current_operation = Some(operation);
-
-            while let Some(mut operation) = current_operation.take() {
-                user_interface.operate(renderer, operation.as_mut());
-
-                match operation.finish() {
-                    operation::Outcome::None => {}
-                    operation::Outcome::Some(()) => {}
-                    operation::Outcome::Chain(next) => {
-                        current_operation = Some(next);
-                    }
-                }
-            }
-        }
-        Action::LoadFont { bytes, channel } => {
-            // TODO: Error handling (?)
-            compositor.load_font(bytes);
-
-            let _ = channel.send(Ok(()));
-        }
-        Action::Output(message) => {
-            messages.push(message);
-        }
-    }
-}
diff --git a/winit/src/application/state.rs b/winit/src/application/state.rs
deleted file mode 100644
index a0a06933..00000000
--- a/winit/src/application/state.rs
+++ /dev/null
@@ -1,221 +0,0 @@
-use crate::application;
-use crate::conversion;
-use crate::core::mouse;
-use crate::core::{Color, Size};
-use crate::graphics::Viewport;
-use crate::runtime::Debug;
-use crate::Application;
-
-use std::marker::PhantomData;
-use winit::event::{Touch, WindowEvent};
-use winit::window::Window;
-
-/// The state of a windowed [`Application`].
-#[allow(missing_debug_implementations)]
-pub struct State<A: Application>
-where
-    A::Theme: application::DefaultStyle,
-{
-    title: String,
-    scale_factor: f64,
-    viewport: Viewport,
-    viewport_version: usize,
-    cursor_position: Option<winit::dpi::PhysicalPosition<f64>>,
-    modifiers: winit::keyboard::ModifiersState,
-    theme: A::Theme,
-    appearance: application::Appearance,
-    application: PhantomData<A>,
-}
-
-impl<A: Application> State<A>
-where
-    A::Theme: application::DefaultStyle,
-{
-    /// Creates a new [`State`] for the provided [`Application`] and window.
-    pub fn new(application: &A, window: &Window) -> Self {
-        let title = application.title();
-        let scale_factor = application.scale_factor();
-        let theme = application.theme();
-        let appearance = application.style(&theme);
-
-        let viewport = {
-            let physical_size = window.inner_size();
-
-            Viewport::with_physical_size(
-                Size::new(physical_size.width, physical_size.height),
-                window.scale_factor() * scale_factor,
-            )
-        };
-
-        Self {
-            title,
-            scale_factor,
-            viewport,
-            viewport_version: 0,
-            cursor_position: None,
-            modifiers: winit::keyboard::ModifiersState::default(),
-            theme,
-            appearance,
-            application: PhantomData,
-        }
-    }
-
-    /// Returns the current [`Viewport`] of the [`State`].
-    pub fn viewport(&self) -> &Viewport {
-        &self.viewport
-    }
-
-    /// Returns the version of the [`Viewport`] of the [`State`].
-    ///
-    /// The version is incremented every time the [`Viewport`] changes.
-    pub fn viewport_version(&self) -> usize {
-        self.viewport_version
-    }
-
-    /// Returns the physical [`Size`] of the [`Viewport`] of the [`State`].
-    pub fn physical_size(&self) -> Size<u32> {
-        self.viewport.physical_size()
-    }
-
-    /// Returns the logical [`Size`] of the [`Viewport`] of the [`State`].
-    pub fn logical_size(&self) -> Size<f32> {
-        self.viewport.logical_size()
-    }
-
-    /// Returns the current scale factor of the [`Viewport`] of the [`State`].
-    pub fn scale_factor(&self) -> f64 {
-        self.viewport.scale_factor()
-    }
-
-    /// Returns the current cursor position of the [`State`].
-    pub fn cursor(&self) -> mouse::Cursor {
-        self.cursor_position
-            .map(|cursor_position| {
-                conversion::cursor_position(
-                    cursor_position,
-                    self.viewport.scale_factor(),
-                )
-            })
-            .map(mouse::Cursor::Available)
-            .unwrap_or(mouse::Cursor::Unavailable)
-    }
-
-    /// Returns the current keyboard modifiers of the [`State`].
-    pub fn modifiers(&self) -> winit::keyboard::ModifiersState {
-        self.modifiers
-    }
-
-    /// Returns the current theme of the [`State`].
-    pub fn theme(&self) -> &A::Theme {
-        &self.theme
-    }
-
-    /// Returns the current background [`Color`] of the [`State`].
-    pub fn background_color(&self) -> Color {
-        self.appearance.background_color
-    }
-
-    /// Returns the current text [`Color`] of the [`State`].
-    pub fn text_color(&self) -> Color {
-        self.appearance.text_color
-    }
-
-    /// Processes the provided window event and updates the [`State`]
-    /// accordingly.
-    pub fn update(
-        &mut self,
-        window: &Window,
-        event: &WindowEvent,
-        _debug: &mut Debug,
-    ) {
-        match event {
-            WindowEvent::Resized(new_size) => {
-                let size = Size::new(new_size.width, new_size.height);
-
-                self.viewport = Viewport::with_physical_size(
-                    size,
-                    window.scale_factor() * self.scale_factor,
-                );
-
-                self.viewport_version = self.viewport_version.wrapping_add(1);
-            }
-            WindowEvent::ScaleFactorChanged {
-                scale_factor: new_scale_factor,
-                ..
-            } => {
-                let size = self.viewport.physical_size();
-
-                self.viewport = Viewport::with_physical_size(
-                    size,
-                    new_scale_factor * self.scale_factor,
-                );
-
-                self.viewport_version = self.viewport_version.wrapping_add(1);
-            }
-            WindowEvent::CursorMoved { position, .. }
-            | WindowEvent::Touch(Touch {
-                location: position, ..
-            }) => {
-                self.cursor_position = Some(*position);
-            }
-            WindowEvent::CursorLeft { .. } => {
-                self.cursor_position = None;
-            }
-            WindowEvent::ModifiersChanged(new_modifiers) => {
-                self.modifiers = new_modifiers.state();
-            }
-            #[cfg(feature = "debug")]
-            WindowEvent::KeyboardInput {
-                event:
-                    winit::event::KeyEvent {
-                        logical_key:
-                            winit::keyboard::Key::Named(
-                                winit::keyboard::NamedKey::F12,
-                            ),
-                        state: winit::event::ElementState::Pressed,
-                        ..
-                    },
-                ..
-            } => _debug.toggle(),
-            _ => {}
-        }
-    }
-
-    /// Synchronizes the [`State`] with its [`Application`] and its respective
-    /// window.
-    ///
-    /// Normally an [`Application`] should be synchronized with its [`State`]
-    /// and window after calling [`crate::application::update`].
-    pub fn synchronize(&mut self, application: &A, window: &Window) {
-        // Update window title
-        let new_title = application.title();
-
-        if self.title != new_title {
-            window.set_title(&new_title);
-
-            self.title = new_title;
-        }
-
-        // Update scale factor and size
-        let new_scale_factor = application.scale_factor();
-        let new_size = window.inner_size();
-        let current_size = self.viewport.physical_size();
-
-        if self.scale_factor != new_scale_factor
-            || (current_size.width, current_size.height)
-                != (new_size.width, new_size.height)
-        {
-            self.viewport = Viewport::with_physical_size(
-                Size::new(new_size.width, new_size.height),
-                window.scale_factor() * new_scale_factor,
-            );
-            self.viewport_version = self.viewport_version.wrapping_add(1);
-
-            self.scale_factor = new_scale_factor;
-        }
-
-        // Update theme and appearance
-        self.theme = application.theme();
-        self.appearance = application.style(&self.theme);
-    }
-}
diff --git a/winit/src/lib.rs b/winit/src/lib.rs
index 3619cde8..3c11b72a 100644
--- a/winit/src/lib.rs
+++ b/winit/src/lib.rs
@@ -5,7 +5,7 @@
 //! `iced_winit` offers some convenient abstractions on top of [`iced_runtime`]
 //! to quickstart development when using [`winit`].
 //!
-//! It exposes a renderer-agnostic [`Application`] trait that can be implemented
+//! It exposes a renderer-agnostic [`Program`] trait that can be implemented
 //! and then run with a simple call. The use of this trait is optional.
 //!
 //! Additionally, a [`conversion`] module is available for users that decide to
@@ -24,24 +24,23 @@ pub use iced_runtime::core;
 pub use iced_runtime::futures;
 pub use winit;
 
-#[cfg(feature = "multi-window")]
-pub mod multi_window;
-
-#[cfg(feature = "application")]
-pub mod application;
 pub mod clipboard;
 pub mod conversion;
 pub mod settings;
 
+#[cfg(feature = "program")]
+pub mod program;
+
 #[cfg(feature = "system")]
 pub mod system;
 
 mod error;
 mod proxy;
 
-#[cfg(feature = "application")]
-pub use application::Application;
 pub use clipboard::Clipboard;
 pub use error::Error;
 pub use proxy::Proxy;
 pub use settings::Settings;
+
+#[cfg(feature = "program")]
+pub use program::Program;
diff --git a/winit/src/multi_window.rs b/winit/src/program.rs
index 8bd8a64d..28cd8e52 100644
--- a/winit/src/multi_window.rs
+++ b/winit/src/program.rs
@@ -10,7 +10,7 @@ use crate::core::mouse;
 use crate::core::renderer;
 use crate::core::widget::operation;
 use crate::core::window;
-use crate::core::{Point, Size};
+use crate::core::{Color, Element, Point, Size, Theme};
 use crate::futures::futures::channel::mpsc;
 use crate::futures::futures::channel::oneshot;
 use crate::futures::futures::executor;
@@ -20,14 +20,12 @@ use crate::futures::subscription::{self, Subscription};
 use crate::futures::{Executor, Runtime};
 use crate::graphics;
 use crate::graphics::{compositor, Compositor};
-use crate::multi_window::window_manager::WindowManager;
-use crate::runtime::multi_window::Program;
 use crate::runtime::user_interface::{self, UserInterface};
 use crate::runtime::Debug;
-use crate::runtime::{Action, Task};
+use crate::runtime::{self, Action, Task};
 use crate::{Clipboard, Error, Proxy, Settings};
 
-pub use crate::application::{default, Appearance, DefaultStyle};
+use window_manager::WindowManager;
 
 use rustc_hash::FxHashMap;
 use std::mem::ManuallyDrop;
@@ -40,19 +38,37 @@ use std::time::Instant;
 /// your GUI application by simply calling [`run`]. It will run in
 /// its own window.
 ///
-/// An [`Application`] can execute asynchronous actions by returning a
+/// A [`Program`] can execute asynchronous actions by returning a
 /// [`Task`] in some of its methods.
 ///
-/// When using an [`Application`] with the `debug` feature enabled, a debug view
+/// When using a [`Program`] with the `debug` feature enabled, a debug view
 /// can be toggled by pressing `F12`.
-pub trait Application: Program
+pub trait Program
 where
+    Self: Sized,
     Self::Theme: DefaultStyle,
 {
-    /// The data needed to initialize your [`Application`].
+    /// The type of __messages__ your [`Program`] will produce.
+    type Message: std::fmt::Debug + Send;
+
+    /// The theme used to draw the [`Program`].
+    type Theme;
+
+    /// The [`Executor`] that will run commands and subscriptions.
+    ///
+    /// The [default executor] can be a good starting point!
+    ///
+    /// [`Executor`]: Self::Executor
+    /// [default executor]: crate::futures::backend::default::Executor
+    type Executor: Executor;
+
+    /// The graphics backend to use to draw the [`Program`].
+    type Renderer: core::Renderer + core::text::Renderer;
+
+    /// The data needed to initialize your [`Program`].
     type Flags;
 
-    /// Initializes the [`Application`] with the flags provided to
+    /// Initializes the [`Program`] with the flags provided to
     /// [`run`] as part of the [`Settings`].
     ///
     /// Here is where you should return the initial state of your app.
@@ -62,13 +78,31 @@ where
     /// load state from a file, perform an initial HTTP request, etc.
     fn new(flags: Self::Flags) -> (Self, Task<Self::Message>);
 
-    /// Returns the current title of the [`Application`].
+    /// Returns the current title of the [`Program`].
     ///
     /// This title can be dynamic! The runtime will automatically update the
     /// title of your application when necessary.
     fn title(&self, window: window::Id) -> String;
 
-    /// Returns the current `Theme` of the [`Application`].
+    /// Handles a __message__ and updates the state of the [`Program`].
+    ///
+    /// This is where you define your __update logic__. All the __messages__,
+    /// produced by either user interactions or commands, will be handled by
+    /// this method.
+    ///
+    /// Any [`Task`] returned will be executed immediately in the background by the
+    /// runtime.
+    fn update(&mut self, message: Self::Message) -> Task<Self::Message>;
+
+    /// Returns the widgets to display in the [`Program`] for the `window`.
+    ///
+    /// These widgets can produce __messages__ based on user interaction.
+    fn view(
+        &self,
+        window: window::Id,
+    ) -> Element<'_, Self::Message, Self::Theme, Self::Renderer>;
+
+    /// Returns the current `Theme` of the [`Program`].
     fn theme(&self, window: window::Id) -> Self::Theme;
 
     /// Returns the `Style` variation of the `Theme`.
@@ -89,7 +123,7 @@ where
         Subscription::none()
     }
 
-    /// Returns the scale factor of the window of the [`Application`].
+    /// Returns the scale factor of the window of the [`Program`].
     ///
     /// It can be used to dynamically control the size of the UI at runtime
     /// (i.e. zooming).
@@ -104,17 +138,49 @@ where
     }
 }
 
-/// Runs an [`Application`] with an executor, compositor, and the provided
+/// The appearance of a program.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Appearance {
+    /// The background [`Color`] of the application.
+    pub background_color: Color,
+
+    /// The default text [`Color`] of the application.
+    pub text_color: Color,
+}
+
+/// The default style of a [`Program`].
+pub trait DefaultStyle {
+    /// Returns the default style of a [`Program`].
+    fn default_style(&self) -> Appearance;
+}
+
+impl DefaultStyle for Theme {
+    fn default_style(&self) -> Appearance {
+        default(self)
+    }
+}
+
+/// The default [`Appearance`] of a [`Program`] with the built-in [`Theme`].
+pub fn default(theme: &Theme) -> Appearance {
+    let palette = theme.extended_palette();
+
+    Appearance {
+        background_color: palette.background.base.color,
+        text_color: palette.background.base.text,
+    }
+}
+/// Runs a [`Program`] with an executor, compositor, and the provided
 /// settings.
-pub fn run<A, E, C>(
-    settings: Settings<A::Flags>,
+pub fn run<P, C>(
+    settings: Settings,
     graphics_settings: graphics::Settings,
+    window_settings: Option<window::Settings>,
+    flags: P::Flags,
 ) -> Result<(), Error>
 where
-    A: Application + 'static,
-    E: Executor + 'static,
-    C: Compositor<Renderer = A::Renderer> + 'static,
-    A::Theme: DefaultStyle,
+    P: Program + 'static,
+    C: Compositor<Renderer = P::Renderer> + 'static,
+    P::Theme: DefaultStyle,
 {
     use winit::event_loop::EventLoop;
 
@@ -128,30 +194,24 @@ where
     let (proxy, worker) = Proxy::new(event_loop.create_proxy());
 
     let mut runtime = {
-        let executor = E::new().map_err(Error::ExecutorCreationFailed)?;
+        let executor =
+            P::Executor::new().map_err(Error::ExecutorCreationFailed)?;
         executor.spawn(worker);
 
         Runtime::new(executor, proxy.clone())
     };
 
-    let (application, task) = {
-        let flags = settings.flags;
-
-        runtime.enter(|| A::new(flags))
-    };
+    let (application, task) = runtime.enter(|| P::new(flags));
 
     if let Some(stream) = task.into_stream() {
         runtime.run(stream);
     }
 
-    let id = settings.id;
-    let title = application.title(window::Id::MAIN);
-
     let (boot_sender, boot_receiver) = oneshot::channel();
     let (event_sender, event_receiver) = mpsc::unbounded();
     let (control_sender, control_receiver) = mpsc::unbounded();
 
-    let instance = Box::pin(run_instance::<A, E, C>(
+    let instance = Box::pin(run_instance::<P, C>(
         application,
         runtime,
         proxy,
@@ -166,6 +226,7 @@ where
     struct Runner<Message: 'static, F, C> {
         instance: std::pin::Pin<Box<F>>,
         context: task::Context<'static>,
+        id: Option<String>,
         boot: Option<BootConfig<C>>,
         sender: mpsc::UnboundedSender<Event<Message>>,
         receiver: mpsc::UnboundedReceiver<Control>,
@@ -174,20 +235,17 @@ where
 
     struct BootConfig<C> {
         sender: oneshot::Sender<Boot<C>>,
-        id: Option<String>,
-        title: String,
-        window_settings: window::Settings,
+        window_settings: Option<window::Settings>,
         graphics_settings: graphics::Settings,
     }
 
     let mut runner = Runner {
         instance,
         context,
+        id: settings.id,
         boot: Some(BootConfig {
             sender: boot_sender,
-            id,
-            title,
-            window_settings: settings.window,
+            window_settings,
             graphics_settings,
         }),
         sender: event_sender,
@@ -204,8 +262,6 @@ where
         fn resumed(&mut self, event_loop: &winit::event_loop::ActiveEventLoop) {
             let Some(BootConfig {
                 sender,
-                id,
-                title,
                 window_settings,
                 graphics_settings,
             }) = self.boot.take()
@@ -213,20 +269,9 @@ where
                 return;
             };
 
-            let should_be_visible = window_settings.visible;
-            let exit_on_close_request = window_settings.exit_on_close_request;
-
-            let window_attributes = conversion::window_attributes(
-                window_settings,
-                &title,
-                event_loop.primary_monitor(),
-                id,
-            )
-            .with_visible(false);
-
-            log::debug!("Window attributes: {window_attributes:#?}");
-
-            let window = match event_loop.create_window(window_attributes) {
+            let window = match event_loop.create_window(
+                winit::window::WindowAttributes::default().with_visible(false),
+            ) {
                 Ok(window) => Arc::new(window),
                 Err(error) => {
                     self.error = Some(Error::WindowCreationFailed(error));
@@ -235,16 +280,17 @@ where
                 }
             };
 
+            let clipboard = Clipboard::connect(&window);
+
             let finish_boot = async move {
                 let compositor =
                     C::new(graphics_settings, window.clone()).await?;
 
                 sender
                     .send(Boot {
-                        window,
                         compositor,
-                        should_be_visible,
-                        exit_on_close_request,
+                        clipboard,
+                        window_settings,
                     })
                     .ok()
                     .expect("Send boot event");
@@ -386,7 +432,12 @@ where
                                 let window = event_loop
                                     .create_window(
                                         conversion::window_attributes(
-                                            settings, &title, monitor, None,
+                                            settings,
+                                            &title,
+                                            monitor
+                                                .or(event_loop
+                                                    .primary_monitor()),
+                                            self.id.clone(),
                                         ),
                                     )
                                     .expect("Create window");
@@ -423,10 +474,9 @@ where
 }
 
 struct Boot<C> {
-    window: Arc<winit::window::Window>,
     compositor: C,
-    should_be_visible: bool,
-    exit_on_close_request: bool,
+    clipboard: Clipboard,
+    window_settings: Option<window::Settings>,
 }
 
 enum Event<Message: 'static> {
@@ -449,62 +499,37 @@ enum Control {
     },
 }
 
-async fn run_instance<A, E, C>(
-    mut application: A,
-    mut runtime: Runtime<E, Proxy<A::Message>, Action<A::Message>>,
-    mut proxy: Proxy<A::Message>,
+async fn run_instance<P, C>(
+    mut program: P,
+    mut runtime: Runtime<P::Executor, Proxy<P::Message>, Action<P::Message>>,
+    mut proxy: Proxy<P::Message>,
     mut debug: Debug,
     mut boot: oneshot::Receiver<Boot<C>>,
-    mut event_receiver: mpsc::UnboundedReceiver<Event<Action<A::Message>>>,
+    mut event_receiver: mpsc::UnboundedReceiver<Event<Action<P::Message>>>,
     mut control_sender: mpsc::UnboundedSender<Control>,
 ) where
-    A: Application + 'static,
-    E: Executor + 'static,
-    C: Compositor<Renderer = A::Renderer> + 'static,
-    A::Theme: DefaultStyle,
+    P: Program + 'static,
+    C: Compositor<Renderer = P::Renderer> + 'static,
+    P::Theme: DefaultStyle,
 {
     use winit::event;
     use winit::event_loop::ControlFlow;
 
     let Boot {
-        window: main_window,
         mut compositor,
-        should_be_visible,
-        exit_on_close_request,
+        mut clipboard,
+        window_settings,
     } = boot.try_recv().ok().flatten().expect("Receive boot");
 
     let mut window_manager = WindowManager::new();
 
-    let _ = window_manager.insert(
-        window::Id::MAIN,
-        main_window,
-        &application,
-        &mut compositor,
-        exit_on_close_request,
-    );
-
-    let main_window = window_manager
-        .get_mut(window::Id::MAIN)
-        .expect("Get main window");
-
-    if should_be_visible {
-        main_window.raw.set_visible(true);
-    }
-
-    let mut clipboard = Clipboard::connect(&main_window.raw);
-    let mut events = {
-        vec![(
-            window::Id::MAIN,
-            core::Event::Window(window::Event::Opened {
-                position: main_window.position(),
-                size: main_window.size(),
-            }),
-        )]
-    };
+    let mut events = Vec::new();
+    let mut messages = Vec::new();
+    let mut actions = 0;
 
     let mut ui_caches = FxHashMap::default();
     let mut user_interfaces = ManuallyDrop::new(build_user_interfaces(
-        &application,
+        &program,
         &mut debug,
         &mut window_manager,
         FxHashMap::from_iter([(
@@ -513,15 +538,19 @@ async fn run_instance<A, E, C>(
         )]),
     ));
 
-    runtime.track(
-        application
-            .subscription()
-            .map(Action::Output)
-            .into_recipes(),
-    );
+    runtime.track(program.subscription().map(Action::Output).into_recipes());
 
-    let mut messages = Vec::new();
-    let mut user_events = 0;
+    let is_daemon = window_settings.is_none();
+
+    if let Some(window_settings) = window_settings {
+        let (sender, _receiver) = oneshot::channel();
+
+        proxy.send_action(Action::Window(runtime::window::Action::Open(
+            window::Id::unique(),
+            window_settings,
+            sender,
+        )));
+    }
 
     debug.startup_finished();
 
@@ -535,7 +564,7 @@ async fn run_instance<A, E, C>(
                 let window = window_manager.insert(
                     id,
                     Arc::new(window),
-                    &application,
+                    &program,
                     &mut compositor,
                     exit_on_close_request,
                 );
@@ -545,7 +574,7 @@ async fn run_instance<A, E, C>(
                 let _ = user_interfaces.insert(
                     id,
                     build_user_interface(
-                        &application,
+                        &program,
                         user_interface::Cache::default(),
                         &mut window.renderer,
                         logical_size,
@@ -591,7 +620,7 @@ async fn run_instance<A, E, C>(
                     event::Event::UserEvent(action) => {
                         run_action(
                             action,
-                            &application,
+                            &program,
                             &mut compositor,
                             &mut messages,
                             &mut clipboard,
@@ -601,7 +630,7 @@ async fn run_instance<A, E, C>(
                             &mut window_manager,
                             &mut ui_caches,
                         );
-                        user_events += 1;
+                        actions += 1;
                     }
                     event::Event::WindowEvent {
                         window_id: id,
@@ -782,6 +811,16 @@ async fn run_instance<A, E, C>(
                         event: window_event,
                         window_id,
                     } => {
+                        if !is_daemon
+                            && matches!(
+                                window_event,
+                                winit::event::WindowEvent::Destroyed
+                            )
+                            && window_manager.is_empty()
+                        {
+                            break 'main;
+                        }
+
                         let Some((id, window)) =
                             window_manager.get_mut_alias(window_id)
                         else {
@@ -801,10 +840,6 @@ async fn run_instance<A, E, C>(
                                 id,
                                 core::Event::Window(window::Event::Closed),
                             ));
-
-                            if window_manager.is_empty() {
-                                break 'main;
-                            }
                         } else {
                             window.state.update(
                                 &window.raw,
@@ -903,7 +938,7 @@ async fn run_instance<A, E, C>(
 
                             // Update application
                             update(
-                                &mut application,
+                                &mut program,
                                 &mut runtime,
                                 &mut debug,
                                 &mut messages,
@@ -913,7 +948,7 @@ async fn run_instance<A, E, C>(
                             // application update since we don't know what changed
                             for (id, window) in window_manager.iter_mut() {
                                 window.state.synchronize(
-                                    &application,
+                                    &program,
                                     id,
                                     &window.raw,
                                 );
@@ -926,15 +961,15 @@ async fn run_instance<A, E, C>(
                             // rebuild UIs with the synchronized states
                             user_interfaces =
                                 ManuallyDrop::new(build_user_interfaces(
-                                    &application,
+                                    &program,
                                     &mut debug,
                                     &mut window_manager,
                                     cached_interfaces,
                                 ));
 
-                            if user_events > 0 {
-                                proxy.free_slots(user_events);
-                                user_events = 0;
+                            if actions > 0 {
+                                proxy.free_slots(actions);
+                                actions = 0;
                             }
                         }
                     }
@@ -947,17 +982,17 @@ async fn run_instance<A, E, C>(
     let _ = ManuallyDrop::into_inner(user_interfaces);
 }
 
-/// Builds a window's [`UserInterface`] for the [`Application`].
-fn build_user_interface<'a, A: Application>(
-    application: &'a A,
+/// Builds a window's [`UserInterface`] for the [`Program`].
+fn build_user_interface<'a, P: Program>(
+    application: &'a P,
     cache: user_interface::Cache,
-    renderer: &mut A::Renderer,
+    renderer: &mut P::Renderer,
     size: Size,
     debug: &mut Debug,
     id: window::Id,
-) -> UserInterface<'a, A::Message, A::Theme, A::Renderer>
+) -> UserInterface<'a, P::Message, P::Theme, P::Renderer>
 where
-    A::Theme: DefaultStyle,
+    P::Theme: DefaultStyle,
 {
     debug.view_started();
     let view = application.view(id);
@@ -970,13 +1005,13 @@ where
     user_interface
 }
 
-fn update<A: Application, E: Executor>(
-    application: &mut A,
-    runtime: &mut Runtime<E, Proxy<A::Message>, Action<A::Message>>,
+fn update<P: Program, E: Executor>(
+    application: &mut P,
+    runtime: &mut Runtime<E, Proxy<P::Message>, Action<P::Message>>,
     debug: &mut Debug,
-    messages: &mut Vec<A::Message>,
+    messages: &mut Vec<P::Message>,
 ) where
-    A::Theme: DefaultStyle,
+    P::Theme: DefaultStyle,
 {
     for message in messages.drain(..) {
         debug.log_message(&message);
@@ -994,24 +1029,24 @@ fn update<A: Application, E: Executor>(
     runtime.track(subscription.map(Action::Output).into_recipes());
 }
 
-fn run_action<A, C>(
-    action: Action<A::Message>,
-    application: &A,
+fn run_action<P, C>(
+    action: Action<P::Message>,
+    application: &P,
     compositor: &mut C,
-    messages: &mut Vec<A::Message>,
+    messages: &mut Vec<P::Message>,
     clipboard: &mut Clipboard,
     control_sender: &mut mpsc::UnboundedSender<Control>,
     debug: &mut Debug,
     interfaces: &mut FxHashMap<
         window::Id,
-        UserInterface<'_, A::Message, A::Theme, A::Renderer>,
+        UserInterface<'_, P::Message, P::Theme, P::Renderer>,
     >,
-    window_manager: &mut WindowManager<A, C>,
+    window_manager: &mut WindowManager<P, C>,
     ui_caches: &mut FxHashMap<window::Id, user_interface::Cache>,
 ) where
-    A: Application,
-    C: Compositor<Renderer = A::Renderer> + 'static,
-    A::Theme: DefaultStyle,
+    P: Program,
+    C: Compositor<Renderer = P::Renderer> + 'static,
+    P::Theme: DefaultStyle,
 {
     use crate::runtime::clipboard;
     use crate::runtime::system;
@@ -1047,12 +1082,6 @@ fn run_action<A, C>(
             window::Action::Close(id) => {
                 let _ = window_manager.remove(id);
                 let _ = ui_caches.remove(&id);
-
-                if window_manager.is_empty() {
-                    control_sender
-                        .start_send(Control::Exit)
-                        .expect("Send control action");
-                }
             }
             window::Action::Drag(id) => {
                 if let Some(window) = window_manager.get_mut(id) {
@@ -1266,19 +1295,24 @@ fn run_action<A, C>(
 
             let _ = channel.send(Ok(()));
         }
+        Action::Exit => {
+            control_sender
+                .start_send(Control::Exit)
+                .expect("Send control action");
+        }
     }
 }
 
 /// Build the user interface for every window.
-pub fn build_user_interfaces<'a, A: Application, C>(
-    application: &'a A,
+pub fn build_user_interfaces<'a, P: Program, C>(
+    application: &'a P,
     debug: &mut Debug,
-    window_manager: &mut WindowManager<A, C>,
+    window_manager: &mut WindowManager<P, C>,
     mut cached_user_interfaces: FxHashMap<window::Id, user_interface::Cache>,
-) -> FxHashMap<window::Id, UserInterface<'a, A::Message, A::Theme, A::Renderer>>
+) -> FxHashMap<window::Id, UserInterface<'a, P::Message, P::Theme, P::Renderer>>
 where
-    C: Compositor<Renderer = A::Renderer>,
-    A::Theme: DefaultStyle,
+    C: Compositor<Renderer = P::Renderer>,
+    P::Theme: DefaultStyle,
 {
     cached_user_interfaces
         .drain()
@@ -1300,7 +1334,7 @@ where
         .collect()
 }
 
-/// Returns true if the provided event should cause an [`Application`] to
+/// Returns true if the provided event should cause a [`Program`] to
 /// exit.
 pub fn user_force_quit(
     event: &winit::event::WindowEvent,
diff --git a/winit/src/multi_window/state.rs b/winit/src/program/state.rs
index dfd8e696..a7fa2788 100644
--- a/winit/src/multi_window/state.rs
+++ b/winit/src/program/state.rs
@@ -2,16 +2,16 @@ use crate::conversion;
 use crate::core::{mouse, window};
 use crate::core::{Color, Size};
 use crate::graphics::Viewport;
-use crate::multi_window::{self, Application};
+use crate::program::{self, Program};
 use std::fmt::{Debug, Formatter};
 
 use winit::event::{Touch, WindowEvent};
 use winit::window::Window;
 
-/// The state of a multi-windowed [`Application`].
-pub struct State<A: Application>
+/// The state of a multi-windowed [`Program`].
+pub struct State<P: Program>
 where
-    A::Theme: multi_window::DefaultStyle,
+    P::Theme: program::DefaultStyle,
 {
     title: String,
     scale_factor: f64,
@@ -19,13 +19,13 @@ where
     viewport_version: u64,
     cursor_position: Option<winit::dpi::PhysicalPosition<f64>>,
     modifiers: winit::keyboard::ModifiersState,
-    theme: A::Theme,
-    appearance: multi_window::Appearance,
+    theme: P::Theme,
+    appearance: program::Appearance,
 }
 
-impl<A: Application> Debug for State<A>
+impl<P: Program> Debug for State<P>
 where
-    A::Theme: multi_window::DefaultStyle,
+    P::Theme: program::DefaultStyle,
 {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("multi_window::State")
@@ -39,13 +39,13 @@ where
     }
 }
 
-impl<A: Application> State<A>
+impl<P: Program> State<P>
 where
-    A::Theme: multi_window::DefaultStyle,
+    P::Theme: program::DefaultStyle,
 {
-    /// Creates a new [`State`] for the provided [`Application`]'s `window`.
+    /// Creates a new [`State`] for the provided [`Program`]'s `window`.
     pub fn new(
-        application: &A,
+        application: &P,
         window_id: window::Id,
         window: &Window,
     ) -> Self {
@@ -121,7 +121,7 @@ where
     }
 
     /// Returns the current theme of the [`State`].
-    pub fn theme(&self) -> &A::Theme {
+    pub fn theme(&self) -> &P::Theme {
         &self.theme
     }
 
@@ -195,14 +195,14 @@ where
         }
     }
 
-    /// Synchronizes the [`State`] with its [`Application`] and its respective
+    /// Synchronizes the [`State`] with its [`Program`] and its respective
     /// window.
     ///
-    /// Normally, an [`Application`] should be synchronized with its [`State`]
+    /// Normally, a [`Program`] should be synchronized with its [`State`]
     /// and window after calling [`State::update`].
     pub fn synchronize(
         &mut self,
-        application: &A,
+        application: &P,
         window_id: window::Id,
         window: &Window,
     ) {
diff --git a/winit/src/multi_window/window_manager.rs b/winit/src/program/window_manager.rs
index 57a7dc7e..fcbf79f6 100644
--- a/winit/src/multi_window/window_manager.rs
+++ b/winit/src/program/window_manager.rs
@@ -2,28 +2,28 @@ use crate::core::mouse;
 use crate::core::window::Id;
 use crate::core::{Point, Size};
 use crate::graphics::Compositor;
-use crate::multi_window::{Application, DefaultStyle, State};
+use crate::program::{DefaultStyle, Program, State};
 
 use std::collections::BTreeMap;
 use std::sync::Arc;
 use winit::monitor::MonitorHandle;
 
 #[allow(missing_debug_implementations)]
-pub struct WindowManager<A, C>
+pub struct WindowManager<P, C>
 where
-    A: Application,
-    C: Compositor<Renderer = A::Renderer>,
-    A::Theme: DefaultStyle,
+    P: Program,
+    C: Compositor<Renderer = P::Renderer>,
+    P::Theme: DefaultStyle,
 {
     aliases: BTreeMap<winit::window::WindowId, Id>,
-    entries: BTreeMap<Id, Window<A, C>>,
+    entries: BTreeMap<Id, Window<P, C>>,
 }
 
-impl<A, C> WindowManager<A, C>
+impl<P, C> WindowManager<P, C>
 where
-    A: Application,
-    C: Compositor<Renderer = A::Renderer>,
-    A::Theme: DefaultStyle,
+    P: Program,
+    C: Compositor<Renderer = P::Renderer>,
+    P::Theme: DefaultStyle,
 {
     pub fn new() -> Self {
         Self {
@@ -36,10 +36,10 @@ where
         &mut self,
         id: Id,
         window: Arc<winit::window::Window>,
-        application: &A,
+        application: &P,
         compositor: &mut C,
         exit_on_close_request: bool,
-    ) -> &mut Window<A, C> {
+    ) -> &mut Window<P, C> {
         let state = State::new(application, id, &window);
         let viewport_version = state.viewport_version();
         let physical_size = state.physical_size();
@@ -76,18 +76,18 @@ where
 
     pub fn iter_mut(
         &mut self,
-    ) -> impl Iterator<Item = (Id, &mut Window<A, C>)> {
+    ) -> impl Iterator<Item = (Id, &mut Window<P, C>)> {
         self.entries.iter_mut().map(|(k, v)| (*k, v))
     }
 
-    pub fn get_mut(&mut self, id: Id) -> Option<&mut Window<A, C>> {
+    pub fn get_mut(&mut self, id: Id) -> Option<&mut Window<P, C>> {
         self.entries.get_mut(&id)
     }
 
     pub fn get_mut_alias(
         &mut self,
         id: winit::window::WindowId,
-    ) -> Option<(Id, &mut Window<A, C>)> {
+    ) -> Option<(Id, &mut Window<P, C>)> {
         let id = self.aliases.get(&id).copied()?;
 
         Some((id, self.get_mut(id)?))
@@ -97,7 +97,7 @@ where
         self.entries.values().last()?.raw.current_monitor()
     }
 
-    pub fn remove(&mut self, id: Id) -> Option<Window<A, C>> {
+    pub fn remove(&mut self, id: Id) -> Option<Window<P, C>> {
         let window = self.entries.remove(&id)?;
         let _ = self.aliases.remove(&window.raw.id());
 
@@ -105,11 +105,11 @@ where
     }
 }
 
-impl<A, C> Default for WindowManager<A, C>
+impl<P, C> Default for WindowManager<P, C>
 where
-    A: Application,
-    C: Compositor<Renderer = A::Renderer>,
-    A::Theme: DefaultStyle,
+    P: Program,
+    C: Compositor<Renderer = P::Renderer>,
+    P::Theme: DefaultStyle,
 {
     fn default() -> Self {
         Self::new()
@@ -117,26 +117,26 @@ where
 }
 
 #[allow(missing_debug_implementations)]
-pub struct Window<A, C>
+pub struct Window<P, C>
 where
-    A: Application,
-    C: Compositor<Renderer = A::Renderer>,
-    A::Theme: DefaultStyle,
+    P: Program,
+    C: Compositor<Renderer = P::Renderer>,
+    P::Theme: DefaultStyle,
 {
     pub raw: Arc<winit::window::Window>,
-    pub state: State<A>,
+    pub state: State<P>,
     pub viewport_version: u64,
     pub exit_on_close_request: bool,
     pub mouse_interaction: mouse::Interaction,
     pub surface: C::Surface,
-    pub renderer: A::Renderer,
+    pub renderer: P::Renderer,
 }
 
-impl<A, C> Window<A, C>
+impl<P, C> Window<P, C>
 where
-    A: Application,
-    C: Compositor<Renderer = A::Renderer>,
-    A::Theme: DefaultStyle,
+    P: Program,
+    C: Compositor<Renderer = P::Renderer>,
+    P::Theme: DefaultStyle,
 {
     pub fn position(&self) -> Option<Point> {
         self.raw
diff --git a/winit/src/proxy.rs b/winit/src/proxy.rs
index 0ab61375..d8ad8b3f 100644
--- a/winit/src/proxy.rs
+++ b/winit/src/proxy.rs
@@ -81,8 +81,19 @@ impl<T: 'static> Proxy<T> {
     where
         T: std::fmt::Debug,
     {
+        self.send_action(Action::Output(value));
+    }
+
+    /// Sends an action to the event loop.
+    ///
+    /// Note: This skips the backpressure mechanism with an unbounded
+    /// channel. Use sparingly!
+    pub fn send_action(&mut self, action: Action<T>)
+    where
+        T: std::fmt::Debug,
+    {
         self.raw
-            .send_event(Action::Output(value))
+            .send_event(action)
             .expect("Send message to event loop");
     }
 
diff --git a/winit/src/settings.rs b/winit/src/settings.rs
index 2e541128..78368a04 100644
--- a/winit/src/settings.rs
+++ b/winit/src/settings.rs
@@ -1,25 +1,15 @@
 //! Configure your application.
-use crate::core::window;
-
 use std::borrow::Cow;
 
 /// The settings of an application.
 #[derive(Debug, Clone, Default)]
-pub struct Settings<Flags> {
+pub struct Settings {
     /// The identifier of the application.
     ///
     /// If provided, this identifier may be used to identify the application or
     /// communicate with it through the windowing system.
     pub id: Option<String>,
 
-    /// The [`window::Settings`].
-    pub window: window::Settings,
-
-    /// The data needed to initialize an [`Application`].
-    ///
-    /// [`Application`]: crate::Application
-    pub flags: Flags,
-
     /// The fonts to load on boot.
     pub fonts: Vec<Cow<'static, [u8]>>,
 }