Scrollable class?

Team,

As I have been working on scroll_box and scroll_bar I have had some
concerns / thoughts I want some feedback on.

As things are now, a scroll_box is simply a viewport with 2
scroll_bars.  This works great for images and maybe spreadsheets, but
not much else.  It seems to me that the things we will want in a
scrollbox are: text_area, list, spreadsheet?, viewport... anything
else?  Would it make sense to create a "scrollable" base class and have
each of these derive from that?  That way a scroll_box would be able to
use the scroll_models of each of the concrete scrollable classes, rather
than just that of viewport.  (You can't place a list or text_area in a
viewport and get the expected results).

Thoughts / Flames / Comments ?

Darren