Thanks for the suggestion, but maybe I didn't explain myself as well as I thought. I tried to say that I basically want control over the shape of the viewable area, while allowing for browser resizing and fullscreen mode.
I want it to be letterbox on monitors that aren't as wide as the layout, and pillarbox on monitors that are wider than the layout... and in doing this the viewable area would, of course, need to be centered vertically and horizontally.
I don't really understand how unbounded scrolling is related to this, and I would prefer to not have to sacrifice this option in order to get it working the way I want... hence the 'suggestion' for it to be built into C2 as a feature.
In any case, in fiddling with this, I've just realised that I can't get any HUD type object to scale properly when exporting as fullscreen in browser... but I'm far too tired to work it out now.