A couple of problems with the cygwin version,
 xemacs -vanilla,
 - M-x customize-face default
 	Right-click on [State]. Select "Show all display specs"
 	-> Invalid function: "Show all display specs" 
I would guess that Jan's customize fixes are responsible for this. Stephen?
 - M-x toggle-buffer-file-coding-system
 	Doesn't seem to change buffer-file-coding-system
 	Previously used to toggle how CR-LF was handled.
 	Wait, I just confirmed that this is not working under 21.4.5 as
 well. 
I sometimes see the problem where it sometimes works and sometimes doesn't.
However,
a simple test works for me. It may be that having non-binary mounts affects
things.
       Hmm. This could be a problem with my setup...
 xemacs,
 - customization of Font Family of default face is not honored. I had
 previously customized it to "Letter Gothic MT". Under 21.4.5, it is
 displayed as "Letter Gothic MT". Under 21.4.6-rc1, it is displayed as
 "Courier New". 
Ditto Jan's changes. I don't think this would be caused by my customize fix.
Stephen?
andy