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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