More multiple editor bogosity!

[<TIM at MIT-MC>]

In ZWEI in Release 5.0, Experimental MIT 1.4, FEP 18, 
on Lisp Machine Keith Moon (3600):

When there are two editor frames, and one of them has its typeout window
exposed, the other one is COMPLETELY USELESS!!!  After "selecting" the
other editor, all of the typein still goes to the "deselected one."  Why
is there really only one editor with several panes even though it looks
like there are several of them.  If this is a real pain to fix, I'll
settle for a brief explanation of why it loses the way it does.