The example on ZCS 6.0:Zimlet Developers Guide:Examples:Tab iFrame - Zimbra :: Wiki does not help if the Voice and Preferences tabs are to contain iframes.
Once Voice or Preferences tab is clicked an iframe should be invoked to display the content.
Also, the overview and toolbar should go away as the iframe expected to occupy the entire main content, overview and toolbar area.
Any help in this regard is highly appreciated.