How to force GoBalloon recalculate?

From my understanding, the Background of GoBalloon is only recalculated when GoBalloon is moved.
But in my program, I made some other use of GoBalloon, ending up requiring to update the Background shape under other scenarios besides moving.
So in GoBalloon, is there a method to force a recalculation of the Background shape?

Call LayoutChildren(null).

Works. Thanks.