bug#38778: 26.3; next-error-highlight set to t doesn't seem semi-permanent

[Howard Melman <hmelman@gmail.com>]

I tried this with emacs -Q on a mac using Gnu Emacs 26.3.

Using customize-variable I set next-error-highlight to t ("Semipermanent
highlighting") and saved that value for the current session.

I then ran M-x grep and got a *grep* buffer and moved through the errors
using n and p. The matches appeared in another window and were
highlighted but the highlighting disappeared after a short time (could
be the default value of 0.5 seconds) even if I didn't hit a key.

My understanding of next-error-highlight is when set to t, the
highlighting should remain until I enter another command. Yet 
it seems to disappear on it's own.

Howard


In GNU Emacs 26.3 (build 1, x86_64-apple-darwin18.2.0, NS appkit-1671.20 Version 10.14.3 (Build 18D109))
of 2019-09-02 built on builder10-14.porkrind.org
Windowing system distributor 'Apple', version 10.3.1671
Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Creating customization items...
Creating customization items ...done
Resetting customization items...done
Creating customization setup...done
To install your edits, invoke [State] and choose the Set operation
ls does not support --dired; see ‘dired-use-ls-dired’ for more details.
Grep finished with matches found
File local-variables error: (void-function python-black-on-save-mode)

Configured using:
'configure --with-ns '--enable-locallisppath=/Library/Application
Support/Emacs/${version}/site-lisp:/Library/Application
Support/Emacs/site-lisp' --with-modules'

Configured features:
NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES THREADS

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

Major mode: Python

Minor modes in effect:
  diff-auto-refine-mode: t
  shell-dirtrack-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  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
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny rfc822 mml mml-sec epa
derived epg epg-config gnus-util rmail rmail-loaddefs mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils vc-git
diff-mode easy-mmode python tramp-sh tramp tramp-compat tramp-loaddefs
trampver parse-time format-spec advice auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json shell pcomplete
grep compile comint ansi-color ring map seq byte-opt gv bytecomp
byte-compile cconv dired dired-loaddefs thingatpt help-fns radix-tree
help-mode cus-edit easymenu cus-start cus-load wid-edit cl-loaddefs
cl-lib elec-pair time-date tooltip eldoc electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel term/ns-win ns-win ucs-normalize
mule-util term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page 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 kqueue cocoa ns multi-tty make-network-process emacs)

Memory information:
((conses 16 259054 13300)
(symbols 48 24850 2)
(miscs 40 179 325)
(strings 32 44096 2342)
(string-bytes 1 1289500)
(vectors 16 40807)
(vector-slots 8 789749 12026)
(floats 8 79 548)
(intervals 56 2073 0)
(buffers 992 17))