<Page>
  <Page.actionBar>
    <ActionBar title="Navigation Button">
      <NavigationButton text="ios back" android.systemIcon = "ic_menu_back" tap="navTap"/>
    </ActionBar>
  </Page.actionBar>
  
  <StackLayout>
    <Button text="button" tap="buttonTap"/>
    <Button text="change icon visibility" tap="visibilityTap"/>
  </StackLayout>
</Page>