anchor.diff:      }
       
       header.addComponent(element, prepend: true);
  +  }
  +  
  +  void addFooterComponent(BaseComponent element, {bool prepend: false}) {
  +    if (content == null) {
  +      _pendingFooterElements.add(element);
  +      
  +      return;
  +    }
  +    
  +    footer.addComponent(element, prepend: true);
     }
     
     void _addListeners(Element e) {
  
positive.code:   
    final List<BaseComponent> _pendingHeaderElements = <BaseComponent>[];
    final List<BaseComponent> _pendingContentElements = <BaseComponent>[];
    
    //---------------------------------
    //
  
negative.code:       _pendingContentElements.clear();
      }
      
      if (_pendingFooterElements.isNotEmpty) {
        _pendingFooterElements.forEach((BaseComponent E) => footer.addComponent(E));
        
        _pendingFooterElements.clear();
      }
      
      resizeHandleGroup.addComponent(new Spacer()..percentHeight = 100.0..width = 1);
      resizeHandleGroup.addComponent(resizeHandle);
      
  