[plt-scheme] Scrollbar in version 370

At Wed, 30 May 2007 22:22:37 -0400, Rainer Gross wrote:
> Since I've updated to the latest plt version I have trouble with a  
> canvas% implementation. I use the on-scroll method to update some  
> values, but since version 370 my update method (on-scroll) is called  
> only after I release the scrollbar.

This was a bug in MrEd with 3m, now fixed in SVN.

An internal static variable wasn't registered with the GC. Normally,
that sort of bug leads to a crash. In this case, the variable's value
was only used with `eq?', so there was no crash, but the `eq?'
comparison failed after the 3m GC moved the value.

Thanks,
Matthew