Subject: 27.0.50; hl-line and line-numbers out of sync

From: Andrey Orst <[email-masked]>
Date: Mon, 21 Oct 2019 11:27:58 +0300

Hello, I've encountered this bug, when scrolling with mouse in inactive
window makes hl-line and current line number go out of sync. Can be
reproduced with this minimal config:

emacs -q --eval "(progn
                   (hl-line-mode t)
                   (set-face-attribute 'line-number-current-line nil
:foreground \"#FF0000\")
                   (display-line-numbers-mode t)
                   (split-window-right)
                   (switch-to-buffer \"*Messages*\"))"

This will open two windows, one with *scratch* and other with *Messages*
buffer. Try pasting some long text into the *scratch* buffer, and
scrolling with mouse wheel. The current line number and hl-line
highlighting should be in sync.

Then focus window with *Messages* buffer, and try scrolling in *scratch*
buffer again with mouse wheel. You'll notice that after scrolling the view
beyond the point, current line number remains correct, while hl-line
highlighter
doesn't move:

It looks like, while Emacs always keeps the point in the view, hl-line
acts like editors that alow point to leave the view, but only when
buffer is not in focus.

In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.12,
cairo version 1.17.3)
 of 2019-10-21 built on s06
Repository revision: 435eb82e7b7e8926a3675bac74713e7c6081f7db
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12005000
System Description: Arch Linux

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
 --with-sound=alsa --with-modules --without-gconf --without-gsettings
 --enable-link-time-optimization --with-x-toolkit=gtk3 --without-xaw3d
 --without-m17n-flt --with-cairo --without-compress-install
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -flto=jobserver
 -fuse-linker-plugin -fuse-ld=gold' CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GLIB NOTIFY INOTIFY ACL
GNUTLS LIBXML2 FREETYPE HARFBUZZ LIBOTF ZLIB TOOLKIT_SCROLL_BARS GTK3
X11 XDBE XIM MODULES THREADS LIBSYSTEMD JSON PDUMPER LCMS2 GMP

Important settings:
  value of $LC_MONETARY: en_US.UTF-8
  value of $LC_NUMERIC: en_US.UTF-8
  value of $LC_TIME: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Messages

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
epg-config gnus-util rmail rmail-loaddefs text-property-search time-date
subr-x seq byte-opt gv bytecomp byte-compile cconv mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
display-line-numbers hl-line tooltip eldoc electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel term/x-win x-win term/common-win x-dnd
tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
newcomment text-mode elisp-mode lisp-mode prog-mode register page
tab-bar menu-bar rfn-eshadow isearch timer select scroll-bar mouse
jit-lock font-lock syntax facemenu font-core term/tty-colors frame
cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan thai
tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian
slovak czech european ethiopic indian cyrillic chinese composite
charscript charprop case-table epa-hook jka-cmpr-hook help simple abbrev
obarray minibuffer cl-preloaded nadvice loaddefs button faces cus-face
macroexp files text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget hashtable-print-readable backquote threads
dbusbind inotify lcms2 dynamic-setting font-render-setting cairo
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 47006 4760)
 (symbols 48 6042 1)
 (strings 32 15494 1649)
 (string-bytes 1 504455)
 (vectors 16 10013)
 (vector-slots 8 129547 9758)
 (floats 8 24 35)
 (intervals 56 214 0)
 (buffers 1000 11))