Subject: 25.0.92; Follow mode scrolling broken -- scrolls only one page
From: Anders Lindgren <[email-masked]>
To: [email-masked]
Date: Sat, 23 Apr 2016 19:25:06 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi!

In Emacs 25.0.92, the command `follow-scroll-up' and `follow-scroll-down'
only scroll one page. The intention is that they should scroll as many
pages as there are windows in the window group (i.e. the number of windows
showing the same buffer in the current frame, when follow-mode is enabled),
as was done in Emacs 24.

Steps to repeat:

    emacs -Q
    C-h t
    M-x follow-delete-other-windows-and-split RET
      ;; Page 1 and 2 are visible.
    C-c . C-v
      ;; Now, page 2 and 3 are visible.

I expect page 3 and 4 to be visible.

The idea behind `follow-scroll-up' and `follow-scroll-down' is to scroll
away the entire window group at once. For example, if you have six side by
side windows, `follow-scroll-up' should go from displaying page 1 .. 6 to 7
.. 12. Currently Emacs 25 go from 1 .. 6 to 2 .. 7.

    -- Anders

Ps. I'm the original author of Follow mode, but I haven't been involved in
recent development.

In GNU Emacs 25.0.92.6 (x86_64-apple-darwin14.5.0, NS appkit-1348.17
Version 10.10.5 (Build 14F1713))
 of 2016-04-10 built on macpro.lan
Repository revision: 0e7bcec103073eceecc2621c19e4d290b2d97e8d
Windowing system distributor 'Apple', version 10.3.1348
Configured using:
 'configure --with-ns --without-dbus'

Configured features:
NOTIFY ACL ZLIB TOOLKIT_SCROLL_BARS NS

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

Major mode: Fundamental

Minor modes in effect:
  follow-mode: t
  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
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Preparing tutorial ...
Resume your last saved tutorial? (y or n) n
You can run the command ‘follow-scroll-up’ with C-c . C-v

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired format-spec rfc822 mml
mml-sec password-cache epg epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util help-fns mail-prsvr mail-utils follow
tutorial help-mode easymenu cl-loaddefs pcase cl-lib time-date mule-util
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel ns-win ucs-normalize term/common-win tool-bar dnd fontset image
regexp-opt fringe tabulated-list newcomment elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow timer select scroll-bar
mouse jit-lock font-lock syntax facemenu font-core 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 charscript case-table epa-hook
jka-cmpr-hook help simple abbrev 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 kqueue cocoa ns multi-tty
make-network-process emacs)

Memory information:
((conses 16 196924 8312)
 (symbols 48 19718 0)
 (miscs 40 48 196)
 (strings 32 15395 5251)
 (string-bytes 1 449890)
 (vectors 16 33084)
 (vector-slots 8 650906 6707)
 (floats 8 158 31)
 (intervals 56 196 0)
 (buffers 976 12))