Re: Allowing point to be outside the window?

[Alan Mackenzie]

Hello, Po.

On Sun, Nov 28, 2021 at 16:13:46 +0800, Po Lu wrote:
> Eli Zaretskii <eliz@gnu.org> writes:

> >> From: Po Lu <luangruo@yahoo.com>
> >> Date: Sun, 28 Nov 2021 11:07:57 +0800

> >> I wonder what would be involved in allowing point to be outside a
> >> window's visible area.

Why would anybody want this?  Why do you want this?  This isn't a
rhetorical question.  Because other programs do it isn't a satisfactory
reason.

I detest this behaviour, and that Emacs doesn't (currently) do it is a
large part of the reason why I use Emacs.  With these other programs I
experience a constant background stress, that the careless or accidental
depression of a key causes BANG!!! and the text I was reading
disappears for ever, being overwritten by the text around point.

Also, as Eli has asked, how would you bring point back into the
currently displayed window position?  Please assume the user doesn't
have a mouse, or dislikes using it.  It would also be good to have some
means of setting the mark there.

> > Two steps:

> >   1. Design the feature: how would it work? which operations would
> >      bring point back into the viewport, and which won't?  For
> >      example, a simple question: if point is outside of the viewport,
> >      what is the effect of C-f or C-n on display?

> The effect would be move point forward, or to the next line, and then to
> recenter the window, so point is at the center of the window.

In other words, a complete replacement of the window's previously
displayed text by other text some arbitrary distance away.  This is what
I dislike so much, so hopefully this part of the feature would be
optional.

> Inserting text should probably recenter the window as well, if point is
> outside the visible area (this is also how other programs behave).

Again, this doesn't seem a good reason.

> This is how other programs behave as well.

> > IMO, it's a large job if done cleanly.  Patches welcome.

> Thanks, I will take a look at it.

I think Eli was underestimating when he said it would be a large job.
;-)

-- 
Alan Mackenzie (Nuremberg, Germany).