mail fragility screws all

[Elijah Millgram <Millgram at MIT-OZ>]

I did control-X M to send mail in the editor,
got prompted for a subject when I tried to send,
tried to go back and edit the text, and got wedged.
REALLY wedged.  I couldn't get the ZMAIL main window,
couldn't get menus in PEEK, couldn't get into any of my
ZMACS buffers... 

1)  The system should allow you to go back and modify your
text.

2)  It shouldn't break when you try to do it.

3)  Breakage should be repairable -- i.e., it shouldn't break
EVERYTHING.