gssapi/krb5 absent tgt

[diskin]

We're looking to release a mail and a calendar client that are upgraded to 
use gssapi/krb5 rather than krb4, but there appears to be a significant 
difference between Mac behavior and Win32.  It may be I'm not configuring 
everything correctly, but it looks like Macs will pop up a krb5 login 
dialog when no TGT is present in the cache, but Windows boxes will return 
error messages.  It looks like there may have been a difference of opinion 
in the past on the correct behavior in this situation; prior posts indicate 
that gssapi does not concern itself with obtaining authentication tokens 
for the indicated mechanism when they are absent.
I've run my Win32 tests against the most recently released Win32 binaries, 
2.5.  So my question is:  is the behavior I'm seeing, the absence of a 
login dialog on Win32, the correct and expected behavior?  And if it is, 
are there any simple compile flags that might allow KfW to behave like KfM?
Thanks,
Gregg