Thanks for responding.

After more investigation, it turns out that hl-line-mode is not responsible
for this - I was having this issue in emacs -Q whenever emacs redrew text
(which just happened much more frequently in hl-line-mode). Sometimes it
would disappear, and sometimes it would duplicate the last line when
scrolling down. I tried using Gnome on Wayland instead of X and did not
experience this issue. But other things did not work in wayland.

Since the Arch Wiki (https://wiki.archlinux.org/index.php/intel_graphics)
suggests that the kernel modesetting may be better than the intel graphics
package, I uninstalled that package just to see if that would fix the
issue. After uninstalling and rebooting the computer, I have not
experienced this weird disappearing/duplicating text issue.

I don't know enough about this to tell whether this is a bug in that intel
graphics package or emacs.

Thanks again!

On Mon, Sep 19, 2016 at 11:39 AM Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Alex Branham <alex.branham@gmail.com>
> > Date: Sun, 18 Sep 2016 19:50:22 +0000
> >
> > From emacs -Q:
> > M-x global-hl-line-mode
> > then open a file and move around with C-n
> >
> > Text at the current line disappears seemingly at random. It comes back
> eventually and/or if I do C-l.
> >
> > It does this regardless of major mode and I experienced the behavior in
> 24.5 and 25.1
>
> I cannot reproduce this at all, with neither of the 2 versions.
>