As was mentioned previously, we use third-party libraries to provide the tab GUI support and they don't support multiple rows of tabs, so this would take a fair bit of work for us to implement.
This feature could possibly get implemented in the future, but it's not currently on the product roadmap.
A feature that's in development is a dockable Active Sessions manager, which shows a list of the currently open sessions and each session's connected status. Clicking on a session in the list activates it. This feature is almost ready for external testing. If you would like to try it, please email me at Maureen.Jett@vandyke.com