bug#4041: 23.0.92; Emacs 23: buffer point is no longer frame-local

[Steve Yegge <stevey@google.com>]

1) emacs -q  (with non-nil window-system)
2) find-file /usr/share/dict/words
   - any file longer than ~3x the frame height should serve to demonstrate
   - in remaining steps I'll call this file buffer BUF
3) (goto-char (/ (point-max) 2))
4) (new-frame)
5) (other-frame)  ; if necessary to put point in new frame
6) switch to buffer BUF
7) (goto-char (point-min))
8) switch to buffer *scratch* (or any other buffer)
9) switch to buffer BUF

Observe that point has returned to (/ (point-max) 2).

In Emacs 22, buffer point behaved as if it were frame-local:
at step 9, point would still be at (point-min).

This change may seem innocuous, but it can be quite frustrating and
mysterious if you have a multi-tty frame open at another site.
The buffer point behaves as if it's "stuck":  every time you switch
away from the buffer and return, the point has returned to its
sticky position.

The behavior exhibits in both multi-tty and single-tty flavors, but
is easier to trigger in a long-running multi-tty session distributed
over multiple sites (e.g. home and work).  It was serious enough to


In GNU Emacs 23.0.92.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.12.9)
 of 2009-04-14 on stevey.krc.corp.google.com
Windowing system distributor `The X.Org Foundation', version 11.0.60900000
configured using `configure  '--prefix=/home/stevey/no_crawl/emacs-cvs''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: C
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: C
  value of $LC_NUMERIC: C
  value of $LC_TIME: C
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  shell-dirtrack-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<help-echo> <help-echo> M-x s h e l l <return> C-x 
k <return> C-x b A <return> C-x k <return> C-x C-f 
C-a C-k / u s r / s h a r e / d i c t / w o r <tab> 
<return> C-x 2 C-x e M-> M-v M-v M-v C-r s t e C-a 
C-u C-r ^ s C-a C-x RET n e w - f r <tab> C-e C-a M-x 
n e w - f r <tab> <return> <switch-frame> <help-echo> 
<help-echo> <help-echo> C-x 2 C-x o C-x t M-< C-x b 
<return> C-x b w o <tab> <return> C-x o M-< C-x o C-v 
C-v C-v C-v C-v C-v C-v C-x o C-x 1 C-x b <return> 
C-x b w o <tab> <return> <switch-frame> M-x e <backspace> 
r e p o r t - e m a c s - b u g <tab> <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Note: file is write protected
kmacro-call-macro: No kbd macro has been defined
Mark set
Mark saved where search started [2 times]
Buffer is read-only: #<buffer words> [5 times]
indent-relative: Buffer is read-only: #<buffer words>
Mark set [2 times]