I solved some problem for the ajax version, I added the refresh property
in every definition
<property name='refresh'>3000000</property>
and it works well, but I'm experiencing another problem, it works only on internet explorer, firefox has a strange behaviour sometime it loads everything, sometime all iframes are equal sometime all is empty.
I think it could be a problem in the com_zimbra_html zimlet, is there any new version of this zimlet ?