anchor.diff:  
       return new Scaffold(
         appBar: new AppBar(
  -        title: const Text('New event'),
  +        title: new Text(_hasName ? _eventName : 'Event Name TBD'),
           actions: <Widget> [
             new FlatButton(
               child: new Text('SAVE', style: theme.textTheme.body1.copyWith(color: Colors.white)),
  
positive.code:   DateTime _toDateTime = new DateTime.now();
    bool _allDayValue = false;
    bool _saveNeeded = false;
  
    Future<bool> _onWillPop() async {
      if (!_saveNeeded)
        return true;
  
  
negative.code:           children: <Widget>[
              new Container(
                padding: const EdgeInsets.symmetric(vertical: 8.0),
                alignment: Alignment.bottomLeft,
                child: new TextField(
                  decoration: const InputDecoration(
                    labelText: 'Event name',
                    filled: true
                  ),
                  style: theme.textTheme.headline,
                  onChanged: (String value) {
                    setState(() {
                      _hasName = value.isNotEmpty;
                      if (_hasName) {
                        _eventName = value;
                      }
                    });
                  }
                )
              ),
              new Container(
                padding: const EdgeInsets.symmetric(vertical: 8.0),
                alignment: Alignment.bottomLeft,
                child: new TextField(
                  decoration: const InputDecoration(
                    labelText: 'Location',
                    hintText: 'Where is the event?',
                    filled: true
                  ),
                  onChanged: (String value) {
                    setState(() {
                      _hasLocation = value.isNotEmpty;
                    });
                  }
                )
              ),
              new Column(
                crossAxisAlignment: CrossAxisAlignment.start,
  