at want to support additional set properties
 must ensure that the base class <code>setProperties()</code>
 method is still called.  A typical implementation that supports
 extra properties <code>foo</code> and <code>bar</code> would look
 something like this:</p>
 <pre>
 protected void setProperties(UIComponent component) {
   super.setProperties(component);
   if (foo != null) {
     component.setAttribute("foo", foo);
   }
   if (bar != null) {
     component.setAttribute("bar", bar);
   }
 }
 </pre>

 <