bug: cannot create an unfocused window on Mac for dev

[swarnimarun]

Bevy version

v0.14.1

[Optional] Relevant system information

On, MacOS 14.2.1

SystemInfo { os: "MacOS 14.2.1 ", kernel: "23.2.0", cpu: "Apple M1 Pro", core_count: "8", memory: "16.0 GiB" }

What you did

Setting focused false doesn't work when running app from terminal.

        .add_plugins(DefaultPlugins.set(WindowPlugin {
            primary_window: Some(Window {
            	present_mode: bevy::window::PresentMode::Immediate,
                // ignore this two, set as I am using multiple monitors
                position: WindowPosition::Centered(MonitorSelection::Index(0)),
                focused: false, // here!
                ..default()
            }),
            ..default()
        }))

What went wrong

Ideally the window should not grab focus when set to focused false or so I understand from the docs, I might be wrong. In that case I would like an set_active false flag. And maybe we can reword the docs a bit better.

Additional information

You can fix it if you build the event loop directly by setting, with_activate_ignoring_other_apps to false, but I am not sure how to do this with bevy. (better described here, rust-windowing/winit#3072)

I can't seem to be able to access the event loop in any way.
So it might not be a bug, just a skill issue on my part. But I think even if we could, it's at best a workaround.

It's nice to be able to do it, as I can set cargo watch -x run and see my changes instantly. Especially for game jam projects which are small and require quick tweaks/iteration.

Aside:
Awesome work on the project, appreciate the effort from all the bevy folks, I lack time to write my own libs for my hobby indie game dev projects in Rust. So it's awesome to have such a impressive go-to-ish library in Rust for it. :)

[TheOddler]

I'm having this problem now too on Linux. Did you ever find a working workaround?

[ridleywinters]

I'm neither a Rust nor Bevy expert so this is MacOS specific and probably not the best way to do it (for example, it feels incorrect to introduce a new field when Window already has a focused field), but I was able to locally patch Bevy 0.16 to get the behavior I wanted for launching my application from the terminal in an unfocused state.

Hopefully this helps others and/or someone more familar with Bevy than me may be able to generalize this for inclusion in the repo.

Add a activate_without_focus field to WinitPlugin

pub struct WinitPlugin<T: Event = WakeUp> {
    /// Allows the window (and the event loop) to be created on any thread
    /// instead of only the main thread.
    ///
    /// See [`EventLoopBuilder::build`](winit::event_loop::EventLoopBuilder::build) for more information on this.
    ///
    /// # Supported platforms
    ///
    /// Only works on Linux (X11/Wayland) and Windows.
    /// This field is ignored on other platforms.
    pub run_on_any_thread: bool,

/*-------- new code vvv ---------*/
    /// Allows the window to be created without taking focus if another application
    /// already has focus.
    ///
    /// # Supported platforms
    ///
    /// Only works on macOS.
    /// This field is ignored on other platforms.
    pub activate_without_focus: bool,
/*-------- new code ^^^ ---------*/

    marker: PhantomData<T>,
}

Add a MacOS specific call to the Winit plugin

    fn build(&self, app: &mut App) {
        ...

        #[cfg(target_os = "android")]
        {
            ...
        }

/*-------- new code vvv ---------*/
        #[cfg(target_os = "macos")]
        {
            use winit::platform::macos::EventLoopBuilderExtMacOS;
            event_loop_builder.with_activate_ignoring_other_apps(!self.activate_without_focus);
        }
/*-------- new code ^^^ ---------*/

        let event_loop = event_loop_builder
            .build()
            .expect("Failed to build event loop");

In the application startup code

    let mut winit_plugin = WinitPlugin::<WakeUp>::default();
    winit_plugin.activate_without_focus = true;

    let code = App::new()
        .add_plugins(
            DefaultPlugins.set(winit_plugin),
        )
        .run();

[ariofrio]

Thanks @ridleywinters for the suggestion! I gave an integrated fix a go here:

• Respect Window::focused when requesting macOS app activation on startup and window creation #24702

[ariofrio]

For reference, @TheOddler, spawning focused: false explicitly doesn't support Linux due to lack of support in winit. I'm not sure what it would take to support it.