It would be great to have the possibility to render a drop-down next to all tabs in a TabGroup to use as an overview of currently invisible (but open) tabs. Would be great if it could be realized as part of the component, eg telling the TabGroup how many tabs it can show and any more that are opened push some of the already open ones to the drop-down.
If this can't be realized as one component, it should at least be possible to reserve some space on the same 'line' as the tabs in the TabGroup to render a drop-down (or a menu or something similar) so users can implement the above functionality themselves.
One hint from the mailing-list:
I think this should be included in the TabGroupRenderer. – Bernd Bohmann