bug#52231: 29.0.50; pixel-scroll-precision-mode conflicts with scroll-margin

[Yuan Fu]

It seems that if I set scroll-margin to, say, 4, and enable
pixel-scroll-precision-mode, the screen keeps jumping back while I
scroll down.

To reproduce, run

(progn (setq scroll-margin 4)
       (pixel-scroll-precision-mode))

And scroll down a buffer with mouse wheel.


In GNU Emacs 29.0.50 (build 1, x86_64-apple-darwin21.1.0, NS appkit-2113.00 
Version 12.0.1 (Build 21A559))
of 2021-11-29 built on Brown
Repository revision: 50379fb78d04deb9f422b906add126219a1a775d
Repository branch: master
Windowing system distributor 'Apple', version 10.3.2113
System Description:  macOS 12.0.1

Configured using:
'configure --with-pdumper=yes --with-ns'

Configured features:
ACL DBUS GLIB GNUTLS JSON LCMS2 LIBXML2 MODULES NOTIFY KQUEUE NS PDUMPER
PNG RSVG THREADS TOOLKIT_SCROLL_BARS WEBP XIM ZLIB

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

Major mode: Lisp Interaction

Minor modes in effect:
  pixel-scroll-precision-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  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 emacsbug message mailcap yank-media rmc puny
dired dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068
epg-config gnus-util rmail rmail-loaddefs auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json map
text-property-search seq gv byte-opt bytecomp byte-compile cconv
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 vc-dispatcher cus-start cus-load
pixel-scroll time-date subr-x cl-loaddefs cl-lib 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 keymap
hashtable-print-readable backquote threads dbusbind kqueue cocoa ns
lcms2 multi-tty make-network-process emacs)

Memory information:
((conses 16 68311 11915)
(symbols 48 8127 1)
(strings 32 22000 2025)
(string-bytes 1 680470)
(vectors 16 14059)
(vector-slots 8 189764 11196)
(floats 8 177 333)
(intervals 56 548 1)
(buffers 992 13))