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

[Romanos Skiadas]

Hi Eli,

See inline.

On 12/10/17 09:29, Eli Zaretskii wrote:

Cc: 27647@debbugs.gnu.org, jonaswestlund101@gmail.com,
 npostavs@users.sourceforge.net
From: Romanos Skiadas <rom.skiad@gmail.com>
Date: Wed, 11 Oct 2017 21:32:06 +0100

echo "foo" > /tmp/test.txt

(cd /tmp && git clone https://github.com/emacs-evil/evil)

Add this to a file, eg /tmp/test-init.el:

 (add-hook 'text-mode-hook (lambda () (display-line-numbers-mode)))
 (add-to-list 'load-path "/tmp/evil")
 (require 'evil)
 (evil-mode 1)

 emacs -Q -l /tmp/test-init.el /tmp/test.txt

Put this in the test.txt buffer an eval it:
(let ((overlay (make-overlay 1 6 nil t nil))) ;; flyspell does this on misspelled words
  (overlay-put overlay 'help-echo "a"))

Make sure you are in normal more (press ESC)
Move the mouse above the f at the start of the buffer and hover until the "a" shows up.
Click and drag along toward to end of the line. The line numbers consistently go away with this recipe for me.

Doesn't happen here with the latest emacs-26 branch.  Are you using
that branch, or are you using some other code base for Emacs?

I used Emacs26@078fb7f6df4178d5a35243dad164cdd196392e71

(I didn't clone the evil Git repository; instead, I downloaded a zip
archive and unpacked it on my system.  I don't think it should
matter.)

As long at that is the latest evil, which is what I tested with, that shouldn't matter

Can you tell the details of your build?  If it's a GTK build, does the
problem go away if you tell Emacs to use non-GTK tooltips (by setting
x-gtk-use-system-tooltips to nil), or if you turn off scroll-bar-mode?

It is indeed a GTK3 build and setting x-gtk-use-system-tooltips to nil does indeed make this problem go away. I've set it to nil on my init file for now.

The list of configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 LCMS2

I'll start dissecting evil to see what causes this.

Thanks.