bug#8355: 24.0.50; Boxes in mode-line and scrolling

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> I installed a partial fix for this.  It improves the situation, in
> that for many starting positions of point, the sequence of N C-v's
> followed by N M-v's, or vice versa, will now end up in the same line
> and the same screen position.  There are still cases where we end up
> short by one line, and I don't see how that could be fixed as long as
> the buffer has some stretches of lines with smaller or larger height.
>
> Please try the latest master; if the improvement is sufficient, we can
> close this bug.

I tried it now, and it's a lot more consistent now than it was before.
Before it was almost always off by one line, but now it's correct most
of the time.

I tried this on something that has more dramatic line height
differences, and the phenomenon is more noticeable there -- when
scrolling downwards, things are very predictable, but when scrolling
backwards, Emacs seems to decide to scroll a couple of screenfuls when
there's large images in the buffer, and you have to C-v twice to get
back to where you were.

Should I make a test case?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no