[plt-scheme] hint for debugging file navigator freezing bug in DrScheme 4.1.1, english, on Windows XP Professional, Service Pack 2

From: Benjamin L.Russell (DekuDekuplex at Yahoo.com)
Date: Thu Oct 9 23:26:30 EDT 2008

As has already been discussed on this mailing list, there remains a
bug in DrScheme on Windows XP Professional, Service Pack 2, that
periodically causes the file navigator (the dialog box that opens to
navigate directories whenever opening or saving a file) to freeze for
a few seconds when navigating directories.  It has been causing much
frustration when saving files in a busy, time-pressured environment.
This bug has been persisting since at least v372, and has not yet been
resolved in v4.1.1, either.

This is the problem:  In DrScheme on Windows XP Professional, Service
Pack 2, when I try to open or save a file and need to navigate through
a folder hierarchy, at first the file navigator seems to work fine.
But after navigating through, say, five or six directories, suddenly
the file navigator will freeze and not respond to mouse input for
several seconds (the exact number of seconds varies between three to
eleven or so seconds).  Then it will respond again, only to freeze
again in the same manner after several more seconds.

This causes much pain and grief when rushing to save files before
running to catch the train on my way back home from work (I often
study programming in my spare time after work before running home),
and can cause a risk of missing the train if the freezing becomes too

Previously, discussion of this bug had led to the hypothesis that
perhaps it had been caused by Windows itself as a result of navigating
through local folders on a networked computer.

However, two days ago, I happened to install and try out a very
similar programming tool, newLISP v.9.4.5, which has an almost
identical file navigator, and discovered that that tool does not
freeze under the same conditions.  Therefore, it seems that this bug
is not caused by Windows.

Therefore, apparently it must be some kind of bug in DrScheme itself.

Given that the same bug does not occur in a very similar file
navigator in a very similar programming tool for a very similar
language, newLISP v.9.4.5, can anybody use this information to figure
out a way to debug this bug?  Is there any process in DrScheme that
runs periodically every few seconds that could cause the file
navigator to freeze for several seconds on Windows XP, Service Pack 2?
I enjoy working with DrScheme, and would work with it more if I didn't
have to worry about losing time repeatedly (and possibly missing a
train) because of this frustrating file navigator bug.

-- Benjamin L. Russell

Posted on the users mailing list.