(define my-scheme:text%
  (class scheme:text%
    (override on-char)
    (define on-char
      (lambda (event) 
        (send text-definition insert (send event get-key-code))))
    (super-instantiate ())))
                       

(define definition (instantiate editor-canvas% ($panel-editor)))        
(define text-definition (instantiate my-scheme:text% ()))
(send definition set-editor text-definition)    

this code don't work when i tape on backspace left top ...
any idea?