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 clonehttps://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.