In my project I use dialog inside another dialog box that both dialog I set modal=true that situation click to open dialog box it will open button any action is not performed when I remove modal=true in test2 it will work fine.I use modal in test it not fine.
<p:dialog widgetVar="test1" modal="true"..>
...
<p:commandButton action="#{user.Button1}" oncomplete="PF('test2').show()"/>
</p:dialog>
<p:dialog widgetVar="test2" modal="true"..>
...
<p:commandButton action="#{user.Button2}" oncomplete="PF('test3').show()"/>
</p:dialog>
<p:dialog widgetVar="test3" modal="true"..>
...
</p:dialog>