I got slightly lost between "tabs" and "tags" on your post there.
I could not find that "tabbed" option you were talking about. The latest release 5.2.2 shows that when you go to /admin/ and click configure (/admin/configure) I see the option to choose a template.
Regarding tabs, you should take a look at dotfolio-ui and see the master template implemented there for an example of how you can get the mount points under a subsite into tabs.