[racket] Can I capture the mouse events of canvas% without sub-classing?

Am I right in thinking that while you can add a callback to respond
the on-paint event of canvas% at construction time, i.e..

(new canvas% ...
    [paint-callback (lambda (c e) ...)])

to respond to other events -- mouse, keyboard, etc. -- it is necessary to
sub-class?

E.g.

(define my-canvas%
  (class canvas%
    (define/override (on-event ev)
      (when (send ev button-down? 'left)
        ; do something
    (super-new)))

Or are there alternatives?


Thanks

Dan
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