bug#51251: 29.0.50; Moving cursor on top of raised box leaves artifacts around in NS port

[Po Lu]

Move the cursor over a raised box, like the buttons in a customize
buffer.  Parts of the cursor will remain in the box even after the
cursor is moved out of the button.

I was told that this also occurs on macOS.

I've attached a patch that fixes the problem for me, but it hasn't been
tested on macOS.

(BTW, I'm noticing a general lack of interest in the NS port, where
features from the other ports can take months or even years to land,
especially WRT to GNUStep support.  If there's a list of TODOs with the
NS port, please let me know.  I'd be happy to help bring it up-to-spec.)

Thanks.

0001-Fix-erasing-cursor-on-top-of-raised-boxes-in-NS-port.patch
Description: Text Data

In GNU Emacs 29.0.50 (build 283, x86_64-pc-linux-gnu, NS gnustep-gui-0.29.0)
 of 2021-10-17 built on trinity
Repository revision: e5daab7a59da403c668ac727aaa9177c46b81360
Repository branch: master
Windowing system distributor 'GNU', version 10.3.29
System Description: Fedora 34 (Workstation Edition)

Configured using:
 'configure --with-ns'

Configured features:
ACL DBUS GIF GLIB GMP GNUTLS JPEG JSON LCMS2 LIBSELINUX LIBSYSTEMD
LIBXML2 MODULES NOTIFY INOTIFY NS PDUMPER PNG RSVG SECCOMP SOUND THREADS
TIFF TOOLKIT_SCROLL_BARS XIM ZLIB

Important settings:
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Fundamental

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
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr help-fns radix-tree cl-print debug backtrace
help-mode find-func emacsbug message rmc puny rfc822 mml mml-sec epa
derived epg rfc6068 epg-config gnus-util rmail rmail-loaddefs time-date
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils cus-theme eieio-custom xwidget url-handlers image-mode dired
dired-loaddefs exif browse-url url url-proxy url-privacy url-expand
url-methods url-history url-cookie url-domsuf url-util url-parse
auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache json map url-vars mailcap bookmark text-property-search
wid-browse tree-widget seq gv subr-x byte-opt bytecomp byte-compile
cconv cus-edit pp cus-start cus-load wid-edit cl-loaddefs cl-lib ispell
iso-transl tooltip eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode 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 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 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 emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice button
loaddefs faces cus-face macroexp files window text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads dbusbind inotify gnustep ns
lcms2 multi-tty make-network-process emacs)

Memory information:
((conses 16 96866 10077)
 (symbols 48 10162 1)
 (strings 32 31452 3082)
 (string-bytes 1 950843)
 (vectors 16 19045)
 (vector-slots 8 253053 19351)
 (floats 8 49 45)
 (intervals 56 453 0)
 (buffers 992 15))