[plt-scheme] (Newbie) MrEd modues using Emacs Quack

If I load this code in DrScheme and select Language (module...) and hit the
run button it works (shows the window with the message):
(module test mzscheme
  (require (lib "class.ss") (lib "mred.ss" "mred"))
  (define
   (main)
   (letrec ((frame-155
              (new
               frame%
               (parent #f)
               (alignment '(center top))
               (stretchable-height #t)
               (min-width 0)
               (style '())
               (label "test")
               (width 146)))
            (message-156
              (new
               message%
               (parent frame-155)
               (label "Hello!")
               (style '()))))
     (send frame-155 show #t)))
  (main))

Now, if I load the same code in Emacs quack mode with "mred.exe -z" running,
there is now way I can make it show the window using the code as is (I tried
to evaluate all region, or the last s-exp, nothing helps).
If I remove the "(module test mzscheme " wrapping and start evaluate top
level forms one after another, then by the time I evaluate (send frame-155
show #t) it will run the window without any problem.
My question is how can I develop a module like above in the quack mode
incrementally (adding/removing UI elements)?
Basically, what the best practice of developing MrEd UI in Quack
incrementally?

Thank you,
Andrew
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