[macOS] EventLoop::run_return with multiple windows does not return

[kcking]

Modifying the window_run_return example to spawn multiple windows (but keep a single event loop) results in the event_loop never returning control to the caller. This happens when focusing the non-first window. I have only been testing this on macOS.

// Limit this example to only compatible platforms.
#[cfg(any(
    target_os = "windows",
    target_os = "macos",
    target_os = "linux",
    target_os = "dragonfly",
    target_os = "freebsd",
    target_os = "netbsd",
    target_os = "openbsd"
))]
fn main() {
    use std::{thread::sleep, time::Duration};

    use simple_logger::SimpleLogger;
    use winit::{
        event::{Event, WindowEvent},
        event_loop::EventLoop,
        platform::run_return::EventLoopExtRunReturn,
        window::{Window, WindowBuilder},
    };
    let mut event_loop = EventLoop::new();

    SimpleLogger::new().init().unwrap();
    let _window = WindowBuilder::new()
        .with_title("A fantastic window!")
        .build(&event_loop)
        .unwrap();

    let mut quit = false;

    let mut frame = 0u128;

    let mut windows = vec![];

    while !quit {
        frame += 1;
        event_loop.run_return(|event, _, control_flow| {
            control_flow.set_wait();

            if let Event::WindowEvent { event, .. } = &event {
                // Print only Window events to reduce noise
                println!("{:?}", event);
            }

            match event {
                Event::WindowEvent {
                    event: WindowEvent::CloseRequested,
                    ..
                } => {
                    quit = true;
                }
                Event::MainEventsCleared => {
                    control_flow.set_exit();
                }
                _ => (),
            }
        });

        if frame % 300 == 0 {
            windows.push(Window::new(&event_loop));
        }

        // Sleep for 1/60 second to simulate rendering
        println!("rendering");
        sleep(Duration::from_millis(16));
    }
}

#[cfg(any(target_os = "ios", target_os = "android", target_arch = "wasm32"))]
fn main() {
    println!("This platform doesn't support run_return.");
}

[kcking]

With some debugging I found that the cause appears to be the is_dialog logic in

winit/src/platform_impl/macos/app_state.rs

Line 412 in f3f6f10

let is_visible: BOOL = msg_send![dialog, isVisible];

hard-coding this to false fixes the issue for me, but I'm first going to look further into what this logic is for and if there is a general fix.

[madsmtm]

Thanks for the detailed instructions, makes it very easy to reproduce the issue!