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

_release-content/migration-guides/macos_app_activation.md

@@ -0,0 +1,10 @@
+---
+title: "macOS app activation now follows `Window::focused` on startup and window creation"
+pull_requests: [24702]
+---
+
+On macOS, apps now request activation (to become the active/frontmost app) on startup only if the `WindowPlugin::primary_window` (or any additional `Window` entities available before `WinitPlugin::build`) has `focused: true`. This allows apps to avoid stealing focus from the user by setting `focused: false`.
+
+In addition, apps now request activation when a visible `Window` is created after startup with `focused: true`. Set `focused: false` if you'd prefer the app to remain inactive.
+
+Apps that only use the default `WindowPlugin::primary_window`, which is initially `focused: true` by default, are unchanged.

crates/bevy_winit/src/lib.rs

@@ -109,6 +109,21 @@ impl Plugin for WinitPlugin {
             event_loop_builder.with_any_thread(self.run_on_any_thread);
         }
 
+        #[cfg(target_os = "macos")]
+        {
+            use bevy_ecs::system::SystemState;
+            use winit::platform::macos::EventLoopBuilderExtMacOS;
+
+            // Don't request app activation on startup if all its windows should
+            // start unfocused. Otherwise, app activation would focus one of the
+            // windows.
+            let mut initial_windows_state =
+                SystemState::<Query<(Entity, &Window)>>::new(app.world_mut());
+            let initial_windows = initial_windows_state.get(app.world()).unwrap();
+            let initially_focused = initial_windows.iter().any(|(_, window)| window.focused);
+            event_loop_builder.with_activate_ignoring_other_apps(initially_focused);
+        }
+
         #[cfg(target_os = "windows")]
         {
             use winit::platform::windows::EventLoopBuilderExtWindows;

crates/bevy_winit/src/system.rs

@@ -122,6 +122,14 @@ pub fn create_windows(
                     }
                 }
 
+                #[cfg(target_os = "macos")]
+                {
+                    // Request app activation via `focus_window()` if the window should start focused.
+                    if window.focused {
+                        winit_window.focus_window();
+                    }
+                }
+
                 window_created_events.write(WindowCreated { window: entity });
             }
         });