tabs.addViewController(maps);
tabs.addViewController(bookmarks);
tabs.addViewController(recentStops);
tabs.addViewController(search);
tabs.addVieControllerSelectedHandler(new ViewControllerSelectedHandler() {
@Override
public void handleViewControllerSelected(ViewControllerSelectedEvent event) {
NavigationController nav = (NavigationController) event.getViewController();
nav.popToRootViewController();
}