[racket] Transparent area's

At Mon, 25 Oct 2010 16:41:32 +0200, "Christophe Vandenberghe" wrote:
> Even with a transparent canvas the problem persists. A transparent canvas just 
> adds the background color of it's parent to a bitmap you add. So If you were 
> to put a background image in the canvas that would be fine, but as soon as you 
> want to add another image to it with transparency, the canvas adds the color 
> of the parent background to the transparent pixels.

That doesn't sound right. Can you send some code to illustrate? (You
included a code sketch before, but it was not enough complete enough to
run.)