anchor.diff:      _tabExpandController = null;
     }
   
  -  MaterialTabController _initTabs() {
  +  MaterialTabController _buildTabs() {
       final webLayoutTabController =
           MaterialTabController(MDCTabBar(_webTabBar.element));
       for (final name in ['dart', 'html', 'css']) {
  
positive.code:         .listen((e) => _toggleMenu(_channelsMenu));
    }
  
    MDCMenu _initSamplesMenu() {
      final element = querySelector('#samples-menu')!;
      element.children.clear();
  
      final samples = [
        Sample('e75b493dae1287757c5e1d77a0dc73f1', 'Counter', Layout.flutter),
        Sample('5c0e154dd50af4a9ac856908061291bc', 'Sunflower', Layout.flutter),
        Sample('a1d5666d6b54a45eb170b897895cf757', 'Draggables & physics',
  
negative.code:   final DElement _editorPanelFooter =
        DElement(querySelector('#editor-panel-footer') as DivElement);
    final NewPadDialog _newPadDialog = NewPadDialog();
    late final MDCMenu _samplesMenu = _buildSamplesMenu();
    final DElement _titleElement =
        DElement(querySelector('header .header-gist-name')!);
    late final MaterialTabController _webLayoutTabController = _buildTabs();
    final DElement _webTabBar = DElement(querySelector('#web-tab-bar')!);
    final DElement _webOutputLabel =
        DElement(querySelector('#web-output-label')!);
  