anchor.diff:      reloadGistButton = DisableableButton(querySelector('#reload-gist'), () {
         if (gistId.isNotEmpty) {
           _loadAndShowGist(gistId);
  +      } else {
  +        _resetCode();
         }
       });
  -
  -    reloadGistButton.disabled = gistId.isEmpty;
   
       showHintButton = DisableableButton(querySelector('#show-hint'), () {
         var hintElement = DivElement()..text = context.hint;
  
positive.code:     userCodeEditor.readOnly = value;
      executeButton.disabled = value;
      formatButton.disabled = value;
      reloadGistButton.disabled = value || gistId.isEmpty;
      showHintButton?.disabled = value;
    }
  
  
negative.code:       var type = data['type'];
  
        if (type == 'sourceCode') {
          lastInjectedSourceCode = Map<String, String>.from(data['sourceCode']);
          _resetCode();
        }
      });
    }
  