[plt-scheme] OSX drag-and-drop

As usual, I'm missing something.

 From the documentation it seems like I should be able to create a 
drag-and-drop aware application using MrEd, but I'm not sure what is the 
right way to proceed after my first, naive attempt.

I'm aiming for a droplet; it seems like the same mechanism that enables 
drag-and-drop should lead me to an application that, when embedded in 
MrEd, will give me a droplet.

I'll keep digging. My naive attempt does not work under 208 or 299.22. 
That's not surprising, since I think I'm missing something important.

Thanks,
Matt

(module foo mzscheme
   (require (lib "mred.ss" "mred")
            (lib "class.ss"))

   (define my-frame
     (new
      frame%
      (parent #f)
      (label "Untitled Frame")
      (width 400)
      (height 300)
      ))

   (send my-frame accept-drop-files #t)
   (send my-frame show #t)
   )