canvas tag and image maps.

Iv been playing around with the canvas tag in various browsers and 
noticed something missing that might be useful and I hope could be put 
forward.

Seems none of the browsers I have tried (FF, chrome, opera and safari) 
support using a map with the canvas tag, eg:
<canvas usemap='canvas_map'>

I think this could be useful in a variety of ways, especially using a 
map to predefine hotspots on a canvas based interface without having to 
use javascript to detect where a click has happened, simplifying 
navigation or scripting.