making Fred window not dirty

[mkatz@garnet.berkeley.edu (Michael Katz)]

I have a subclass of *fred-window*.  I don't want to use :scratchp because
most of the time I want to do the normal ask-the-user-to-save-changes thang.

But sometimes I want to make modifications to the window under program control
WITHOUT having the window think it's been modified.  I'm looking for a function
call UNDIRTY, or something like that (or a DIRTY flag I can set to NIL or a
CHANGE-COUNT variable I can set to 0 or ... you get the idea).

Does anybody know how to do this?  Thanks.