code: private synchronized Renderer findRenderer(final WComponent component,
  			final Duplet<String, Class<?>> key) {
  		LOG.info("Looking for layout for " + key.getSecond().getName() + " in " + key.getFirst());
  
  		Renderer renderer = findConfiguredRenderer(component, key.getFirst());
  
  		if (renderer == null) {
  			renderers.put(key, NULL_RENDERER);
  		} else {
  			renderers.put(key, renderer);
  		}
  
  		return renderer;
  	}
docs: Finds the layout for the given theme and component.
  
  @param component the WComponent class to find a manager for.
  @param key the component key to use for caching the renderer.
  @return the LayoutManager for the component.