bug#27647: 26.0.50; Line numbers implemented natively disappear momentarily when frame out of focus

[Romanos Skiadas]

On 05/10/17 14:39, Eli Zaretskii wrote:
> > From: Eli Zaretskii <eliz@gnu.org>
> > Cc: 27647@debbugs.gnu.org, jonaswestlund101@gmail.com,
> >         npostavs@users.sourceforge.net
> >
> > It's most probably something related to some hook or timer that you
> > set up in your customizations.
> Or maybe some feature calls kill-all-local-variables, but doesn't
> restore display-line-numbers until later.
I have been seeing this problem for a while due to something happening 
with flycheck-pos-tip, like in the original report. I disabled the 
package, but today I started seeing it (or could it be something 
different?) again in a buffer. It's far from a recipe, but I was seeing 
this:

- In a buffer, the line numbers looked like attached screenshot (1)
- in a buffer, I pressed any combination of keys that would cause 
which-key to pop up
- I pressed C-g to close which-key. At this point, the line numbers 
would look like screenshot (2). They don't go away per se, it looks like 
something goes wrong in some calculation maybe?
- Pressing C-g restored the line numbers to state (1)

I played with adding debug-watch to a couple of variables, this was a 
few hours ago so I only remember I did it with display-line-numbers and 
nothing showed up. I also did debug-on-entry on 
kill-all-local-variables, it never gets called.

After playing with the buffer for a while, I found out that this 
behaviour goes away with git-gutter-mode disabled. I'll find some time 
to try to get something reproducible with stock Emacs within the next 
couple of days.

@Eli, I still have the buffer around and can try out things. Do you have 
any debugging hints for this?

Best,
Romanos

line_numbers_2.png
Description: PNG image

line_numbers_1.png
Description: PNG image