I think Georgi may have misunderstood what Samuel was looking for.
I'm guessing that Samuel wanted to bind a tooltip to the data source for the rotator but the problem is that since the tooltip in declared inside the rotator item template, the element hierarchy places the tooltip inside the bounding div of the rotator items. The tooltip therefore gets clipped.
I'm trying to get this to work by fooling around with position:absolute css on the tooltip but haven't had any luck yet.
Is there a trick to getting a tooltip to expand when declared inside a RadRotator?