Stay zoomed in an area

I'm trying to keep a viewpoint so that it can't leave a specified area,
like the state of North Carolina.

It's an odd request, but is it possible to make it so that if someone
accidentally zooms outside of the view area, I can rezoom them back? I
was looking for something like, if the bounds exceed a certain lat/lon,
movemap back to the center view.. etc..

Where would I put the listener in to prevent the zooming from going too
far from the focus area?

The whole motivation for this, fyi, isn't to prevent innapropriate
usage (anyone can hit google maps and surf anyway),. It's more about
training. The clients requested this restriction upon themselves to
simply their view.

Thanks!