Test case

<zk>
  <window border="normal" title="hello">
  	<listbox mold="select" id="listbox1">
  		<attribute name="onSelect"><![CDATA[
  			listbox2.getItems().clear(); 
  			listbox2.appendChild(new Listitem("banana")); 
  			listbox2.appendChild(new Listitem("banana2")); 
  			listbox2.invalidate();
  			]]></attribute>  				
          <listitem label="test" selected="true"/>
          <listitem label="test2"/>
    </listbox>
    <listbox id="listbox2" mold="select">
      <listitem label="test1" selected="true"/>
      <listitem label="test2"/>
      <listitem label="test3"/>
    </listbox>
  </window>
</zk>

Steps to reproduce on FF/IE (Chrome works fine)
Step 1: Tab in first listbox
Step 2: Press down arrow key to change selection to "test 2"
Step 3: Tab out of first listbox
Step 4: Press down arrow key to select second listbox value

Expected:
After step 3 above listbox2 should be updated with new values and focus should be on it so the step 4 selection is done
Actual:
After step 3 above listbox2 is updated with new values but focus is lost. Pressing down arrow key does not chage value in listbox2 as focus is removed

Note:
This behavior happens on 5.0.12FL and 6.5FL but works as expected on 6.0.x (for chrome works well on any ZK version)