[plt-scheme] mred: resizable editors in frame%

 hi there, 
 I have a problem, trying to make resizable editors in a frame%. I have a graphical interface, composed of one frame% and two editor-canvas% (his childrens). In each editor-canvas% i've put a text% object. So.. I want, the user to be able to resize the editors in the frame% (just like in DrScheme.. you can resize the definitions windows (increase it and decrease the top-level window with the same, or conversely)), but it dosn't work.
 There is a part of the code:

;the frame
(define frame
  (new frame% (min-width 600) (min-height 300) (label "Untitled") (x 50) (y 50)))

(define hpanelJS
  (new horizontal-panel% (parent frame) (min-width 580) (min-height 230) (stretchable-width #t) (stretchable-height #t)))

;editor1
(define jscript 
  (new editor-canvas% (parent hpanelJS) (stretchable-width #t) (stretchable-height #t)
       (style '(control-border))))

(define jscript-text
  (new text%))

(send jscript set-editor jscript-text)

;editor2
(define hpanelTL
  (new horizontal-panel% (parent frame) (min-width 580) (min-height 70) (stretchable-width #t) (stretchable-height #t)))

(define top-level 
  (new editor-canvas% (parent hpanelTL) (stretchable-width #t) (stretchable-height #t)

       (style '(control-border))))
(define TL-text
  (new text%))

(send top-level set-editor TL-text)

;blabla
(send frame show #t)

 If sombody can help.. I'll be grateful
 thanks