anchor.diff:        (div(c: 'collapse-native-container')
               ..flex()
               ..add([
  -              hideNativeCheckbox,
  +              collapseNativeCheckbox,
                 CoreElement('div', text: 'Collapse native samples')
                   ..element.style.color = colorToCss(contrastForeground),
               ]))
  
positive.code:       }
      });
  
      // Add hide native checkbox to tab nav.
      hideNativeCheckbox =
          CoreElement('input', classes: 'collapse-native-checkbox')
            ..setAttribute('type', 'checkbox');
  
      final html.InputElement checkbox = hideNativeCheckbox.element;
      checkbox
        ..checked = true
        ..onChange.listen(
            (_) => _collapseNativeSamplesController.add(checkbox.checked));
  
  
negative.code: 
    bool canvasNeedsRebuild = false;
  
    bool lastCollapseNativeSamplesValue = _defaultCollapseNativeSamplesValue;
  
    bool showingError = false;
  
  