I've brought this up before, but have noticed something that may help.
The issue is gis.m freezing on Grass-GIS 6.4.0RC5, running on Mac OSX 10.5.8, on a MacBook Pro.
The "freeze process" is:
1. Launch gis.m
2. Grab a corner of the map display to resize it.
3. Pull the corner.
Frequently Wish freezes on (3).
But I have now noticed that while it happens using the trackpad, an external mouse is far less prone to having the freeze.
So could there be something that Wish doesn't like about the trackpad driver or setup?
The oldest report I can find related to this is here:
http://lists.osgeo.org/pipermail/grass-user/2009-September/052304.html
Richard Chirgwin