RE: mouse click on an overlay, using overlay `keymap' property

[Drew Adams]

> > how can foo be defined so that a first click on
> > the displayed "xxxxxxxxx" calls bar?
> 
> How 'bout
> (defun foo (beg end)
>    (interactive "r")
>    (let ((overlay (make-overlay beg end)))
>      (overlay-put
>       overlay 'display
>       (propertize "xxxxxxxxx" 'face 'font-lock-constant-face 
>                               'keymap foo-map))))

I was hoping that that would do the trick and help me understand, but it
doesn't seem to change anything. (Does it work for you?) I'm using Emacs
22.1, FWIW. 

Is this a bug? Can someone please explain what's happening? Thx.