bug#23098: 25.0.92; (recenter -1) can leave point in the middle of the window

[Eli Zaretskii <eliz@gnu.org>]

> From: Jorgen Schäfer <jorgen.schaefer@gmail.com>
> Date: Thu, 24 Mar 2016 16:27:53 +0000
> Cc: 23098@debbugs.gnu.org
> 
> > If you do the above, do you still get the cursor recentered in the
> > window?
> 
> Hm. That seems to work.

OK, so at least we see the same behavior.

> I was using let-binding around recenter, which does not work.

Indeed, it won't work because the value of scroll-conservatively needs
to be seen by redisplay, which runs after the code of the test case
finishes execution.  You could try let-binding it around a call to
'redisplay', but that's probably gross.

>  Even resetting
> scroll-conservatively after the call to recenter will exhibit the bug again. So setting scroll-conservatively is a
> possible workaround, although it means that *all* scrolling will be affected by scroll-conservatively. E.g.
> scrolling through the backlog of a M-x shell session would be affected, even though it just should affect the
> scrolling when the last line of the buffer is visible at all.

Well, setting scroll-conservatively is the only way in Emacs to
reliably avoid recentering of point in all kinds of corner cases.  So
if you cannot use that setting, I'm afraid I'm out of ideas.

Thanks.