Sample code showing that on-subwindow-event does not have correct receiver for message%

message-no-event.rkt

#lang racket/gui

(define my-frame%
  (class frame%
    (define/override (on-subwindow-event receiver event)
      (when (send event button-down?)
        (displayln (send receiver get-label)))
      #f)
    (super-new)))

(define fr (new my-frame% [label "Frame"]))
(define msg (new message%  [parent fr] [label "Message"]))
(define bt (new button%    [parent fr] [label "Button"]))
(define cb (new check-box% [parent fr] [label "Check-box"]))
(define panel (new panel%  [parent fr]))
(send panel set-label "Panel")
(define msg2 (new message% [parent panel] [label "Message 2"]))

(send fr show #t)