bug#12419: Mouse click changes layout

[martin rudalics]

>> So I have to fix this regardless of the topic we're discussing here.
>
> Good!  Though it wouldn't annoy me so much, if it weren't that it
> slightly breaks your patch.  What is important to me, is that when I
> click and let go, the point is where I initially clicked, and since I
> didn't move the mouse, I don't want to mark anything.

I installed a fix by now.  Please try it.

> As for going the "opposite" direction, I wonder if it's worth while to
> keep a history of the last n implicitly changed window configurations
> and try to revert to them wherever possible.  Might be huge task
> admittedly...

Indeed.  And it might not help when the user wants a configuration that
didn't exist yet.  That's why shrinking the minibuffer shrinks it to one
line.  Anything else would require proportional resizing which people
don't like.

> A somewhat related annoyance is that scrolling looses the point:
> scrolling back to where you were before, doesn't revert that. Whenever I
> scroll to somewhere, the point should go where it was last visible
> within those lines, if it had been visible there before!  This should be
> quite straightforward.  Though with sideways scrolling it might be more
> tricky...

Eli already cited a corresponding thread.  As far as sideways scrolling
is concerned do you mean the disabled commands `scroll-left' and
`scroll-right'?  `scroll-restore' doesn't handle these yet but there
should be no problem doing that.

> The "disturbing new" is that (in our C-x 2 scenario) by clicking
> somewhere, the point ends up somewhere else, and without moving the
> mouse I've marked some text.  I'm fairly confident that this is a recent
> degradation.  (Though I don't have an old Emacs to try against to be
> sure.)  Your patch improved it, but not quite fixed it.

Please come up with a precise scenario so I can reproduce it.

> I don't C-x 3 so much, so this might have been there before – I don't
> remember when it first annoyed me.  Just the occasional glitch, which on
> its own never merited heckling anybody about. Actually sideways
> scrolling is only neat when I click near the edge wanting it.  When I
> don't think about it, it's usually a hassle to get things like they were
> before.  Probably it should only sideways scroll when I drag the mouse
> over the window edge, like vertical scrolling.

I suppose the problem with automatic sideways scrolling you see is that
the positions of `point' and the mouse cursor do not coincide after an
autscroll.  But something like this happens all the time.  Start
mouse-marking text somewhere in the middle of a line and move the mouse
down until you encounter an empty line.  `point' will be at the
beginning of the line and the mouse cursor around the column where it
was before.  IIUC, the primary importance here is to keep the mouse
cursor from jumping around.

martin