Subject: 27.0.50; Mouse events assigned to header line while pointer not in header line

From: [email-masked]
Date: Fri, 18 Oct 2019 14:06:40 +0200

On a window with header line (package-list-packages), move the
mouse pointer to the line inmediately below the header line. Move the
mouse wheel, and get the message:

<header-line> <mouse-5> is undefined

Also, clickable items on the header line are highlighted as if the mouse
was over them when the mouse is on the line below.

Tested on X11 and win32.

In GNU Emacs 27.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.24.5)
 of 2019-10-17 built on DESKTOP-M4KH14I
Repository revision: 0a70727c4024ac6a66c378df52e37808ee2d7993
Repository branch: master
Windowing system distributor 'HC-Consult', version 11.0.12005001
System Description: Debian GNU/Linux 10 (buster)

Recent messages:
<header-line> <mouse-5> is undefined [2 times]
<header-line> <mouse-4> is undefined
<header-line> <double-mouse-4> is undefined
<header-line> <mouse-4> is undefined
<header-line> <mouse-5> is undefined
<header-line> <double-mouse-5> is undefined
<header-line> <triple-mouse-5> is undefined [2 times]
<header-line> <mouse-4> is undefined
<header-line> <double-mouse-4> is undefined
<header-line> <triple-mouse-4> is undefined

Configured features:
XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS GLIB NOTIFY INOTIFY
LIBSELINUX GNUTLS FREETYPE HARFBUZZ XFT ZLIB TOOLKIT_SCROLL_BARS GTK3
X11 XDBE XIM MODULES THREADS PDUMPER GMP

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

Major mode: Package Menu

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 sendmail mm-archive message dired
dired-loaddefs rfc822 mml mml-sec epa derived epg mailabbrev gmm-utils
mailheader mm-decode mm-bodies mm-encode mule-util gnutls network-stream
url-http mail-parse rfc2231 url-gw nsm rmc url-cache url-auth epg-config
finder-inf package url-handlers eww easymenu mm-url gnus nnheader
gnus-util rmail rmail-loaddefs rfc2047 rfc2045 ietf-drums time-date
mail-utils wid-edit mm-util mail-prsvr thingatpt url-queue url url-proxy
url-privacy url-expand url-methods url-history mailcap shr
text-property-search url-cookie url-domsuf url-util url-parse
auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache json subr-x map url-vars puny svg xml seq byte-opt gv
bytecomp byte-compile cconv dom browse-url format-spec cl-loaddefs
cl-lib 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 dynamic-setting system-font-setting font-render-setting
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 141251 12804)
 (symbols 48 10551 1)
 (strings 32 36312 1074)
 (string-bytes 1 1041021)
 (vectors 16 16730)
 (vector-slots 8 211137 7692)
 (floats 8 43 220)
 (intervals 56 8123 0)
 (buffers 1000 12))