[racket] Adding "undo" and "redo" to racket/gui menu item

The following code from the racket/gui documentation gives me an "edit"
menu with "copy', "cut","paste","select all","delete"  working but "redo"
and "undo" don't appear to be working.

Do I have to add code to get "undo", "redo" to work in the "edit" menu.  If
so what code do I need to add?

Thanks,
Harry Spier
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#lang racket/gui
(define frame (new frame% [label "Example"]))
(send frame show #t)

(define c (new editor-canvas% [parent frame]))
(define t (new text%))
(send c set-editor t)

(define mb (new menu-bar% [parent frame]))
(define m-edit (new menu% [label "Edit"] [parent mb]))
(define m-font (new menu% [label "Font"] [parent mb]))
(append-editor-operation-menu-items m-edit #t)
(append-editor-font-menu-items m-font)


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