On Sun, Oct 15, 2017 at 9:25 AM Kaushal Modi <kaushal.modi@gmail.com> wrote:

>
> The issue hasn't repeated in the past few days .. I'd hate if this has to
> do with me restarting my machine. (As a side: My machine had an uptime of
> about a year, and I restarting it fixed the problem that gdb wasn't able to
> access ptrace. The whole reason I wanted that to work was to use gdb to
> debug this problem when it occurred next.)
>
> After the machine restart, the gdb issue resolved, and this line
> disappearing issue also "seems" to have.. disappeared.
>

Nope, it is back!

Thanks to Romanos, I tried to see if this issue had anything to do with
tooltips and it almost always happens when hovering mouse over stuff in
modeline, waiting for tooltips to appear.

I have yet to find a recipe from emacs -Q, but below is a GIF recording:

==> https://i.imgur.com/kB6gHDk.gifv <==

- Hovering mouse for tool-tips makes the line nums disappear (only for some
tooltips though)
- Clicking anywhere in the buffer brings the line nums back

I do that a couple of times in that GIF.

@Eli: About setting display-line-numbers globally, that did not help..

I evaluated:

    (setq-default display-line-numbers t)

(So now even fundamental-mode buffers have line numbers.)

But even after, the hover-over-modeline magic trick faithfully reproduces
this issue at least on my config.

Now, I will try to cook an emacs -Q recipe.

=====
Latest emacs version info (Note that I am on RHEL 6.6, GTK2):

Emacs version: GNU Emacs 26.0.90 (build 4, x86_64-pc-linux-gnu, GTK+
Version 2.24.23)
 of 2017-10-16, built using commit 16e85456e70174f1d97fc5a7cd8a199b8f0e7e70.

./configure options:
  --with-modules --prefix=/home/kmodi/usr_local/apps/6/emacs/emacs-26
'--program-transform-name=s/^ctags$/ctags_emacs/'
'CPPFLAGS=-I/home/kmodi/usr_local/6/include -I/usr/include/freetype2
-I/usr/include' 'CFLAGS=-ggdb3 -O0' 'CXXFLAGS=-ggdb3 -O0'
'LDFLAGS=-L/home/kmodi/usr_local/6/lib -L/home/kmodi/usr_local/6/lib64
-ggdb3'

Features:
  XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
GTK2 X11 MODULES
-- 

Kaushal Modi