[plt-scheme] clicking in an editor window

Robby Findler wrote:

> Did you consider actually using slideshow itself?

I hadn't thought of it, and this is certainly the easiest thing to do. 
However, the purpose of Kathi's exercises is to demonstrate how one 
might begin to design and implement something like Slideshow. So using 
it as the back end is somehow unsatisfying, even though the emphasis in 
her development is clearly on the language design. --PR

(PS How do I make sure that the user program does not hang waiting for a 
mouse click in a window that the user has closed instead of clicking in it?)