How to make scroll bars follow text

[David Shifflett <shifflett nps navy mil>]

Hi,
I am using a scrolled window and want to know how to
automatically make the scrollbar (vertical only)
position itself such that last item inserted into
the text field (within the scrolled window) is always
visible at the bottom of the scrolled window.

To put it another way:
The scrolled window shows 10 lines of text at a time.
once the text widget has more than 10 lines in it,
the bottom ten lines should be visible whenever new
text is added to the text widget.

Once the text widget is completely full (say 100 lines)
and I put the scrollbar all the way down manually,
the scrollbar will always show the last text inserted.

How do I make this behavior the default, even before
the text widget is full?

Any help, comments, examples, would be appreciated
Thanks,
David Shifflett