text: XHTML Components
  From Documentation
  This section describes how to use the XHTML component set (i.e., XHTML components). XHTML components are in a different component set than ZUL components. You have to specify XML namespace to distinguish them if you want to use them in the same ZUML document. For example,
  <window xmlns: <h:ul> <h:li>Click <button/></h:li> </h:ul> </window>
  Notice that the HTML component set is one of the approaches to use HTML tags directly in a ZUML document. In most cases, it is not the best approach. For information please refer to ZK Developer's Reference: HTML tags.