Future hintBig(String text, Duration duration)

Shows a big hint label with text in the upper center of the screen for the given duration

Source 

hintBig(String text, Duration duration) async {

    // Setup Label
    final bigLabel = get("bigLabel");
    bigLabel.setInnerHtml(text);

    // Show Label for duration
    await timeout(duration, before: () => activate(bigLabel), after:  () => deactivate(bigLabel));
}