fn app(cx: &mut Context) -> NodeKey {
    Element::new()
        .align_items(AlignItems::Center)
        .justify_content(JustifyContent::Center)
        .child(cx.insert("Hello World!"))
        .build(cx)
}

fn main() {
    viewbuilder::run(app)
}

fn app(cx: &mut Context) -> NodeKey {
    let mut elem = Element::new();
    elem.overflow_y(Overflow::Scroll)
        .flex_direction(FlexDirection::Column)
        .extend((0..100).map(|count| cx.insert(count.to_string())));
    elem.build(cx)
}

fn button(
    cx: &mut Context,
    label: &'static str,
    mut handler: impl FnMut(&mut Context) + 'static,
) -> NodeKey {
    Element::new()
        .on_click(Box::new(move |cx, _event| handler(cx)))
        .background_color(Color4f::new(1., 1., 0., 1.))
        .child(cx.insert(label))
        .build(cx)
}