anchor.diff:  
   
   }
  -void formBlur(MouseEvent e) {
  +void onDimensionInputBlur(MouseEvent e) {
     var target = e.target as HtmlElement;
     target.parent.querySelector('span.${e.currentTarget.className}').text = target.value;
   
  
positive.code: 
  void main() {
    container = querySelector('#container');
    querySelector('#refresh').onClick.listen(refreshPreviewContent);
    querySelector('#url').onChange.listen(refreshPreviewContent);
    createPreview(0, 0, 1024,768,0.5);
    createPreview(520, 0, 320, 480 ,0.8);
    createPreview(0, 420, 1920,1200,0.4);
  
negative.code: 
    var spans = querySelectorAll(".preview form span");
    for (HtmlElement span in spans) {
      span.onClick.listen(onDimensionLabelClick);
    }
    var inputs = querySelectorAll(".preview form input");
    for (HtmlElement input in inputs) {
      input.onBlur.listen(onDimensionInputBlur);
    }
  
  }
  
  void onDimensionLabelClick(Event e) {
    var target = (e.target as HtmlElement);
    var parent = target.parent;
    parent.querySelectorAll("span").style.display = 'none';
  