bevy/examples/window/window_settings.rs

use bevy::prelude::*;
use bevy_window::WindowMode;

/// This example illustrates how to customize the default window settings
fn main() {
    App::build()
        .add_resource(WindowDescriptor {
            title: "I am a window!".to_string(),
            width: 300,
            height: 300,
            vsync: true,
            resizable: false,
            mode: WindowMode::Fullscreen { use_size: false },
            ..Default::default()
        })
        .add_default_plugins()
        .run();
}