Thank for your help.
If wrap combo inside panelGorup:
<h:panelGroup layout="block" rendered="#{ ! empty testManager.selectedItem}" id="suitems">
....
</h:panelGroup>
Using this snip code, result is same first example because div is not rendered too.
My solution has been use "disabled" attribute instead of "rendered" and css:
<style>
.nodisplay_disabled[disabled] { display: none; }
</style>
......
<h:selectOneListbox value="#{testManager.selectedSubItem}" disabled="#{ empty testManager.selectedItem}" styleClass="nodisplay_disabled" id="suitems">
......
[Message sent by forum member 'angelcervera' (angelcervera_at_silyan.com)]
http://forums.java.net/jive/thread.jspa?messageID=384099