Rutime setting scrolling-window field size?

[Malcolm Pradhan <pradhan@camis.stanford.edu>]

I am using the scrolling-window class to display data whose bounds
changes as the user makes various choices. I understand that one can
set the scrolling-window's 'field size', ie. the scroll bar's min and
max, using the initarg :field-size, but it is not clear to me how to
'legally' change it during runtime as the slot is read only.

 Thanks,
 Malcolm