bug#16458: 24.3.50; Slow update of region higlight when Follow mode is used

[Anders Lindgren <andlind@gmail.com>]

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From: Anders Lindgren <anders@macpro.lan>
To: bug-gnu-emacs@gnu.org
Subject: 24.3.50; Slow update of region higlight when Follow mode is used
--text follows this line--

When Follow mode is enabled, the region highlight does not update as fast
as it normally does.

Steps to repeat:

    emacs -Q
    C-h t
    M-x follow-delete-other-windows-and-split RET
    C-SPC
    Press and hold C-n,  release it when the cursor is halfway down the
window.

    Here, the region highlight does not follow the cursor, it appears a
second or so after the key was released.

    Just as a reference, do the same without follow-mode:

    M-x follow-mode RET
    Press and hold C-n and run the cursor to the end of the window.

    This time the region highlight follows the cursor as it is moved around.

It's hard to tell when this problem was introduced, as both cursor movement
and region highlight first worked, then both were broken (slow), then
cursor movement were corrected.

    -- Anders Lindgren


In GNU Emacs 24.3.50.3 (x86_64-apple-darwin13.0.0, NS apple-appkit-1265.00)
 of 2014-01-14 on macpro.lan
Repository revision: 116025
agustin.martin@hispalinux.es-20140114105028-pui5ej728y7cbpt3
Windowing system distributor `Apple', version 10.3.1265
Configured using:
 `configure --with-ns'

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

Major mode: Fundamental

Minor modes in effect:
  follow-mode: t
  tooltip-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 input:
C-h t C-SPC <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <escape>
x f o l l o w - m o d e <return> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <escape> x f o l l o w - d e <tab> <return>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <escape> x <up> <up> <return>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<down> <S-down> <S-down> <S-down> <S-down> <S-down>
<S-down> <S-down> <S-down> <S-down> <S-down> <S-down>
<S-up> <S-up> <S-up> <S-up> <S-up> <S-up> <S-up> <S-up>
<S-up> <S-up> <S-up> <S-up> <S-up> <S-up> <S-up> <up>
<up> <up> C-SPC <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> C-SPC <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <escape>
x f o l l o w - m o <tab> <return> C-SPC <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <s-escape> C-x 1 <escape> x r e p o r t - e
m <tab> <return>

Recent messages:
Preparing tutorial ...
Mark set
Follow mode enabled
You can run the command `follow-delete-other-windows-and-split' with C-c . 1
Follow mode disabled
Mark set [3 times]
Follow mode enabled
Mark set
<s-escape> is undefined
M-o f is undefined

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec 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
time-date tooltip electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel ns-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list newcomment lisp-mode prog-mode register page menu-bar
rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax
facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak
czech european ethiopic indian cyrillic chinese case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer 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 make-network-process cocoa ns multi-tty emacs)

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