Re: User representation of orgls & berts

[Marc Stiegler <acad!xanadu!acad!xanadu!marcs>]

In response to dean's proposal to treat Revert as an edit operation,
I have the following comments:

1) If I understand it correctly, having Revert as an edit operation saves
us from creating a new verb to fulfill the job of Unrevert or Revert Forward.
The existing verb Undo (or "Undo Revert" when the last operation was a
revert) does the job.

2) However, treating Revert as an operation manipulated by the Undo verb
breaks my mental model of traditional user interface behavior in a number
of ways. One I can put my finger on easily is this: with Undo, I expect
to see my display back up by a single small step. But if as I tool through
a series of undos and hit a Revert, all of a sudden a dramatic change 
occurs. Another is symptom of trouble is the time it takes me to parse
the concept "Undo Revert" even with my knowledge of Xanadu--compare it to
another inevitable verb, "Redo Revert". "Redo" is a "take you forward" verb.
AH, but "Redo Revert" is a "take you backward" operation.

Of course, as anyone as Xanadu can tell, my traditional mental model is
just not sophisticated enough. But part of the desire is to avoid
repairing millions of mental models this first time out.

All in all, I have a mild conviction that users will grok a Revert Forward
more easily than they will grok a Redo Revert. Actually, I'm inclined to
bow to Bob Perez's opinion on this matter. Bob?

--marcs