more on scrolled window sizing ... fixes + bugs?

[Paul Davis <pbd op net>]

one more clarification on this.

when the widget that's packed into the scrolled window is a Layout or
a Canvas, things work the way you'd want them to, primarily because
these widgets have a requisition of (0,0) at all times. they change
their size via their adjustments, which the scrolled window can handle.

however, when its a box whose contents are actually increasing, the
object's requisition does increase. even with a viewport wrapped
around it, growing the box when its in a scrolled window with a
POLICY_NEVER for the scrollbars will also grow the scrolled window.

hence, there needs to be some way to distinguish the 2 cases: no, i
don't want scrollbars, yes i want the child's allocation to be
limited. 

--p