In the RadMultipageView a portal URL is set as content. The user navigates to one of the pages within the portal. Now there is no way to go back to previous page or to the default landing page where the tab was initially at.
Requesting a new feature in the tab strip to allow navigate through the iframe history (back/forward) for a multipage view. It could be similar to the back/forward buttons of the browser but within the tab of the tab strip where the content URL is set in the multipage view. This could be set enable/disable by a setting.