Hi,
I don't think there's an easy "switch" to turn on the behaviour you describe. I think you could do it by connecting to the
sigResized signal of the ViewBox, and calculating new values for the visible region and then calling setRange(). There would be a bit of work remembering old values of the ViewBox size, and maybe ignoring the event on initialisation or if your setRange() call also triggers the sigResized signal again.
With a little more work (querying the window position) then you might be able to differentiate between a resize from the top-left or bottom-right corners.
There may be an easier way to do it, but that's the only way I can think of at the moment.
Patrick