anchor.diff:  }
   
   class TabNavigationHelper {
  +  Map<AppTab, GlobalKey<NavigatorState>> navigatorKeys = {
  +    AppTab.profile: GlobalKey<NavigatorState>(),
  +    AppTab.runs: GlobalKey<NavigatorState>(),
  +    AppTab.futureEvents: GlobalKey<NavigatorState>(),
  +    AppTab.pastEvents: GlobalKey<NavigatorState>(),
  +    AppTab.offlineChart: GlobalKey<NavigatorState>()
  +  };
  +
     _HomeState _home;
   
     TabNavigationHelper(this._home);
  
positive.code: 
  enum AppTab { profile, runs, futureEvents, pastEvents, offlineChart }
  
  Map<AppTab, GlobalKey<NavigatorState>> navigatorKeys = {
    AppTab.profile: GlobalKey<NavigatorState>(),
    AppTab.runs: GlobalKey<NavigatorState>(),
    AppTab.futureEvents: GlobalKey<NavigatorState>(),
    AppTab.pastEvents: GlobalKey<NavigatorState>(),
    AppTab.offlineChart: GlobalKey<NavigatorState>()
  };
  
  class Home extends StatefulWidget {
    Home({Key key}) : super(key: key);
  
  
negative.code: class _HomeState extends State<Home> {
    static const TextStyle optionStyle =
        TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
  
    int _selectedIndex = 0;
    TabNavigationHelper _tabHelper;
    List<Widget> _widgetOptions;
  
    set selectedIndex(value) {
      if (value != _selectedIndex) {
  