Marking squares

[Lars Magne Ingebrigtsen]

I'm contemplating implementing a very, very simple image editor in
Emacs, which would mainly just allow image cropping.  To do that, it
would be nice if `mouse-drag-region' would allow highlighting a "box"
instead of the lines between mark and the mouse position.

So my question is -- does Emacs have an option of highlighting
rectangles instead of "the region"?  It might be useful when using
commands like `C-x r k', too, perhaps.

I've looked at the code, but I can't find anything obvious
immediately...

-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/