Is it possible to listen just on the map div? IIRC you need to add the `tabindex="0"` attribute to the div. There's some discussion on Stack Overflow [here](http://stackoverflow.com/questions/148361) and [here](http://stackoverflow.com/questions/10722589).

I don't know much about keyboard event handling, so it's entirely possible that I've missed something important here. Don't hesitate to tell me what it is :)