chosenbox rendering inconsistently and losing selections

running the attached example shows, that already selected items are rendered using the HTML generated in the ItemRenderer, while the choices only display escaped markup.
When selecting a new value the escaped markup is added to the box in the escaped form.

the ItemRenderer API docs state HTML markup is possible http://www.zkoss.org/javadoc/latest/zk/org/zkoss/zul/ItemRenderer.html

When invalidating the chosenbox, previously selected items are lost.