bug#58401: 29.0.50; EWW: kill-word (M-d) in input field gives "Text is read-only"

[Stefan Kangas <stefankangas@gmail.com>]

Severity: minor

Text in a EWW input field is sometimes incorrectly treated as read-only.

0. emacs -Q
1. M-x eww RET foo RET
2. C-n C-n        ;; so that point is on "foo"
3. M-d            ;; kill-word

"foo" is not deleted, instead I get this error message:

    kill-region: Text is read-only: #<buffer *eww*>

The expected result is that "foo" is deleted in the search field.
I've tested this in Emacs 27.1 too, and the result is the same.

(If I type `C-d M-d' in the recipe above instead, I get no warning.)


In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.34, cairo version 1.16.0) of 2022-10-09 built on joffe
Repository revision: a2dd9d683a02525183b5e692e42622c65639dda8
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Debian GNU/Linux bookworm/sid

Configured using:
 'configure --with-native-compilation'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES
NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3
THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
  value of $LC_COLLATE: C
  value of $LC_CTYPE: sv_SE.UTF-8
  value of $LC_TIME: C
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: eww

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-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
  buffer-read-only: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort hashcash mail-extr emacsbug message yank-media dired
dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068 epg-config
mm-decode mm-bodies mm-encode mailabbrev gmm-utils mailheader sendmail
textsec uni-scripts idna-mapping ucs-normalize uni-confusable
textsec-check gnutls network-stream url-http mail-parse rfc2231 rfc2047
rfc2045 ietf-drums url-gw nsm url-cache url-auth format-spec eww xdg
url-queue thingatpt shr pixel-fill kinsoku url-file svg xml dom
browse-url url url-proxy url-privacy url-expand url-methods url-history
url-cookie generate-lisp-file url-domsuf url-util url-parse auth-source
eieio eieio-core password-cache json map byte-opt url-vars mailcap puny
mm-url gnus nnheader gnus-util text-property-search time-date mail-utils
range wid-edit mm-util mail-prsvr cl-loaddefs comp comp-cstr warnings
icons subr-x rx cl-seq cl-macs gv cl-extra help-mode bytecomp
byte-compile cconv cl-lib rmc iso-transl tooltip eldoc paren electric
uniquify ediff-hook vc-hooks lisp-float-type elisp-mode 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 lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer nadvice seq simple cl-generic
indonesian philippine 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 emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
faces cus-face macroexp files window text-properties overlay sha1 md5
base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit xinput2 x multi-tty make-network-process
native-compile emacs)

Memory information:
((conses 16 304930 10184)
 (symbols 48 11311 0)
 (strings 32 64689 2767)
 (string-bytes 1 1553286)
 (vectors 16 47527)
 (vector-slots 8 906391 25074)
 (floats 8 99 108)
 (intervals 56 887 205)
 (buffers 1000 13))