anchor.diff:  // Use of this source code is governed by a BSD-style license that can be
   // found in the LICENSE file.
   
  +import 'dart:async';
   import 'dart:html';
   
   import 'package:flutter_web/material.dart';
  
positive.code:     return Scaffold(
        appBar: AppBar(
          actions: <Widget>[
            IconButton(
              icon: const Icon(Icons.settings),
              tooltip: 'Settings',
  
negative.code:   }
  
    TabController _tabController;
    Timer _changeTabsTimer;
    bool _tabsPaused = false;
  
    @override
    void initState() {
      super.initState();
      _changeTabsTimer = Timer.periodic(const Duration(minutes: 1), _changeTabs);
      _tabController = TabController(vsync: this, length: _dashboardTabs.length);
    }
  
    @override
    void dispose() {
      _changeTabsTimer.cancel();
      _tabController.dispose();
      super.dispose();
    }
  
    Future<void> _changeTabs(Timer timer) async {
      if (_tabsPaused) return;
  
      int nextIndex = _tabController.index + 1;
      if (nextIndex > _dashboardTabs.length - 1) {
        nextIndex = 0;
      }
      _tabController.animateTo(nextIndex);
    }
  
    @override
  