Paul and I talked a little about this today.
The issue is really just a Gui one, not one for the
underlying graphics
system. Both the scrollbar approach and the window content scaling
one can be handled in a very superficial way by device
drivers without
any changes at all to the underlying R graphics system. (I suspect
that this is how Splus adresses the problem).
The behavior I want requires a deeper interaction with the graphics
system, but it is the behavior already in place.
Enabling the behaviors you and Brian prefer is just a
matter of flicking
a switch in the driver so that it no longer tells the
graphics system
when there has been a change in the window configuration and having
the driver handle the scaling or scrolling.
So, everyone can have what they want ...
The real problem is that we don't have enough of a Gui (yet) to make
the behavior happen in a cross-platform way.