code: @Override
  	protected void preparePaintComponent(final Request request) {
  		super.preparePaintComponent(request);
  
  		Class<? extends WComponent> rowRendererClass = getRowRendererClass();
  
  		if (rowRendererClass != null && !expandedRenderers.containsKey(rowRendererClass)) {
  			getExpandedTreeNodeRenderer(rowRendererClass).preparePaint(request);
  		}
  	}
docs: <p>
  The preparePaintComponent method has been overridden to ensure that expanded row renderers have been correctly
  initialised.
  </p>
  <p>
  Expanded row renderers are lazily instantiated and added to the shared structure as needed. This means for the
  first use of a renderer, it will not have been part of the WComponent tree, and would not have had its
  preparePaintComponent called. We therefore add the renderer to the tree here, and manually call its preparePaint.
  </p>
  
  @param request the Request being responded to.