bug#6192: 24.0.50; eldoc-mode: unexpected recentering

[Stephen Berman]

1. Let ~/.emacs consist of the following line:
(add-hook 'emacs-lisp-mode-hook 'turn-on-eldoc-mode)

2. Start Emacs with the above init-file.

3. Visit an Emacs lisp file that's long enough to scroll a number of
screens up and down, e.g. lisp/abbrev.el from the Emacs source
directory.

4. Type `M->' (end-of-buffer).

5. Type 'M-v' (scroll-down-command)

=> This puts point at line 902 (at least here, with window-height 33),
which is at the bottom of the window as it should be -- but only for a
fraction of a second, and then point is recentered so that line 902 is
now in the middle of the window.

On subsequent reiterations of M-v this recentering sometimes happens and
sometimes doesn't.  I haven't discovered a pattern (nor does it happen
the first time with all files, though it appears to be consistent within
the same file).

This recentering only happens when eldoc-mode is enabled from the mode
hook in the user init file, i.e., starting Emacs with -Q and evalling
the sexp in step 1, then doing steps 2-5, I do not observe the
recentering. 


In GNU Emacs 24.0.50.3 (i686-pc-linux-gnu, GTK+ Version 2.18.6)
 of 2010-05-12 on escher
Windowing system distributor `The X.Org Foundation', version 11.0.10605000
configured using `configure  '--without-toolkit-scroll-bars''

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