No, dedicated windows in frames that have other windows are too
troublesome. They often surprise the user.
What is the problem? I do not understand. That little window just exists
when ediff is active on that frame, right?
The problem is that there are too many situations when ediff has to
remember to undedicate or delete that window if the user decides to
postpone the work and do something else.
I still don't understand: why should ediff have to undedicate
that window? Or why should it need to delete it: if it's dedicated
it'll be deleted automatically when the buffer is killed.
There are cases when ediff can be suspended. In that case the small window
should be deleted. There are cases when several ediff sessions are active
at the same time. Doing all this properly with dedicated windows seems too
much trouble with little payoff. But, as I said, I'll take another look to
see if this can be done without major complications.