match event {
            winit::event::Event::WindowEvent {
                event: WindowEvent::Resized(size),
                ..
            } => {
                data.egui_routine
                    .resize(size.width, size.height, window.scale_factor() as f32);
                //  Tell camera about size change.
                data.render_camera_state_link
                    .lock() // brief lock for small scope
                    .unwrap()
                    .update_window_size((size.height as u16, size.width as u16));
            }
            winit::event::Event::WindowEvent {
                event: WindowEvent::CloseRequested {},
                ..
            } => {
                log::warn!("Quitting, window closed.");
                data.scene_quit.store(true, Ordering::Release); // tell other threads

    ...