Re: Overalays and point-entered

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Well, you'd want it to display when you moved to the buffer - If you are
> moving out of the overlay in question with C-x o it may not matter, but if
> you are moving into a window with a buffer that the point is in one of these
> overlays you'd want the action to trigger and display the error message.
> The same applies to C-x b.  This was just the use case I had in mind - there
> are probably others.

IIUC you're saying that it should be run both for C-x o and C-x b, right?
I'd understand that.  I read your earlier answer to say that you wanted
C-x o to do it but not C-x b, which I found puzzling.

Personally, I'd say that in those cases actually it doesn't matter that
much either way: for C-x o, you're going back to a in window that's
already displayed and to a point that's already displayed, so there's
a good chance you've already seen the message earlier.
For C-x b it's less likely, but there's still a fairly good chance as
well, and in either case if you miss a message in those cases it doesn't
seem like too big a problem.

So I think this use-case is unlikely to give us a good and strong
indication of how it should work.

Here's another potential use case: when doing completion inside a buffer
(e.g. completing an identifier in some programming mode), if the
completion brings up a *Completions* buffer, we'd want to hide the
*Completions* buffer when the completion is done, but detecting "when
the completion is done" is difficult, so one way to do it would be to
place a "cursor-leave" hook on the completion area.

Now, what the behavior should be upon C-x o or C-x b is again somewhat
unclear: for C-x b, actually I think it's pretty clear that it should
run the hook (which is a vote in favor of per-window data), but for "C-x
o" it's less clear: running the hook would often be a good idea, but
would mean that it's somewhere between difficult and impossible to let
the user go to the *Completions* buffer to select an entry with
choose-completion.


        Stefan