anchor.diff:      _disabled = value;
       _element.toggleClass(disabledClassName, value);
     }
  +
  +  set hidden(bool value) {
  +    _element.toggleAttr('hidden', value);
  +  }
   }
   
   class Octicon {
  
positive.code: 
      super.selectTab(tabName);
    }
  }
  
  /// A container underneath the tab strip that can show or hide itself as needed.
  
negative.code:     executeButton.disabled = value;
      formatButton.disabled = value;
      reloadGistButton.disabled = value || gistId.isEmpty;
      showHintButton.disabled = value;
    }
  
    Future<void> _loadAndShowGist(String id, {bool analyze = true}) async {
      editorIsBusy = true;
  
      final GistLoader loader = deps[GistLoader];
      final gist = await loader.loadGist(id);
      context.dartSource = gist.getFile('main.dart')?.content ?? '';
      context.testMethod = gist.getFile('test.dart')?.content ?? '';
      context.solution = gist.getFile('solution.dart')?.content ?? '';
      context.hint = gist.getFile('hint.txt')?.content ?? '';
      tabController.setTabVisibility('test', context.testMethod.isNotEmpty);
      showHintButton.hidden = context.hint.isEmpty && context.testMethod.isEmpty;
      editorIsBusy = false;
  
      if (analyze) {
  