[racket] racket 5.2.1 and 5.3

At Sun, 12 Aug 2012 22:03:06 +0200 (CEST), Ivanyi Peter wrote:
> I have just tried version DrRacket 5.2.1 and 5.3 on Windows 7, 
> the 64 bit version, and I have noticed two things:
> - In version 5.2.1 for the canvas% the (send this get-scroll-range 'vertical) 
> does not work. It simple
> fails. No other error message. I was trying to run the MrEdDesigner program. 

I see that `get-scroll-range' fails for a canvas or scroll direction
for which scrollbars are not enabled. I'll fix that.

> - More importantly in version 5.3 what happened to mrtabgroup ???
> How do I create tabs?

Do you mean "mred/private/mrtablegroup.rkt"? It was an empty module in
v5.2.1, and we removed it in v5.3. The `tab-panel%' class is still
available, though.