anchor.diff:        ..layoutVertical()
         ..flex());
       DElement _rightArea = _embedArea.add(new DElement.tag('div'));
  -    DElement _embedDartArea = _leftArea.add(new DElement.tag('div')
  -      ..layoutHorizontal());
  -    DElement _embedHtmlArea = _leftArea.add(new DElement.tag('div')
  -      ..layoutHorizontal());
  +    DElement _embedDartArea =
  +        _leftArea.add(new DElement.tag('div')..layoutHorizontal());
  +    DElement _embedHtmlArea =
  +        _leftArea.add(new DElement.tag('div')..layoutHorizontal());
       _embedDartRadio = _embedDartArea.add(new RadioButtonInputElement()
         ..name = "embed"
         ..id = "dart-radio");
  
positive.code:       ..text = 'Dart + HTML'
        ..style.paddingLeft = '8px');
      _embedDartRadio.checked = true;
      _embedPicture = _rightArea.add(new ImageElement(src: _docThumbnail, height: 100, width: 300)
        ..alt = "Embed-dart"
        ..style.paddingLeft = "16px");
      _embedDartRadio.onClick.listen((_) => _embedToDart());
      _embedHtmlRadio.onClick.listen((_) => _embedToHtml());
      _info = _leftArea.add(new DElement.tag('div')..layoutHorizontal()..flex());
      _info.add(new SpanElement()
        ..text = 'Check out our '
        ..style.fontSize = "12px"
        ..append(new SpanElement()
        ..text = 'embedding guide'
        ..attributes['onClick'] =
      "window.open('https://github.com/dart-lang/dart-pad/wiki/Embedding-Guide')"
        ..style.cursor = "pointer"
        ..style.textDecoration = "underline"
        ..style.fontSize = "12px")
        ..append(new SpanElement()
        ..text = '.'));
    }
  
    void _embedToDart() {
      _embedPicture.src = _docThumbnail;
      _embedPicture.alt = "Embed-dart";
      _embedUrl.value = "<iframe src='https://${home}/embed-dart.html?id=${gistContainer.mutableGist.id}'></iframe>";
    }
  
    void _embedToHtml() {
      _embedPicture.src = _htmlThumbnail;
      _embedPicture.alt = "Embed-html";
      _embedUrl.value = "<iframe src='https://${home}/embed-html.html?id=${gistContainer.mutableGist.id}'></iframe>";
    }
  
    void showWithSummary(String summary) {
  
negative.code:       ..readonly();
      _gistUrl.onClick.listen((_) => _gistUrl.selectAll());
      div = _div.add(new DElement.tag('div', classes: 'row')..layoutHorizontal());
      div.add(new DElement.tag('span', classes: 'sharinglabel'))..text = 'Embed:';
      inputGroup = div.add(new DElement.tag('div'))
        ..layoutHorizontal()
        ..flex();
      _embedUrl = inputGroup.add(new DInput.input(type: 'text'))
        ..flex()
        ..readonly()
        ..value =
        "<iframe src='https://${home}/embed-dart.html?id=${gistContainer.mutableGist.id}'></iframe>";
      _embedUrl.onClick.listen((_) => _embedUrl.selectAll());
      div = _div.add(new DElement.tag('div', classes: 'row')..layoutHorizontal());
      _embedArea = div.add(new DElement.tag('div'))
        ..layoutHorizontal()
        ..flex();
  