Major Description
The scrollbar's handle can't reach the right end.
The same behavior is also in the tutorial (http://pivot.apache.org/tutorials/scroll-bars.html). Try scrolling to the right end and you will see a gap between scrollbar's handle and its "right" button.
Link to thread:
http://apache-pivot-users.399431.n3.nabble.com/Scroll-Bars-td1746186.html#a1746186