Hi Allan Krøyer,
First, yes, our documentation for the client-side API of RadRibbonBar is incomplete yet and we are working on improving that.
Second, since internally RRB uses a RadTabStrip with a RadMultiPage control you can use the APIs of the latter two to manipulate them on the client. Still you should have in mind that we are also working on a simpler TabStrip, which we will incorporate into RRB effectively replacing the RTS and RMP, so it is possible that some of the code for RTS and RMP you use now may not work later. The API of the new TabStrip will be definitely limited and narrower than that of RTS.
I hope this helps. If you have additional questions, please let me know.
the Telerik team