mouse-face redisplay messy on Windows XP x64 Edition

[John Paul Wallington]

I've noticed a weird redisplay bug on Emacs built and run with mingw
on Windows XP x64 Edition for development versions of Emacs built on
2006-09-30 through 2006-10-14.

In a Gnus Summary buffer, mouse-wheel scrolling up and down over
Author's names causes fragments of the highlight mouse-face to remain
after the mouse cursor has left them.

Here's an example screenshot:
http://www.shootybangbang.com/redisplay-mouse-face-bug.png

Although the screenshot shows a customized Emacs, I can reproduce with
emacs -Q and (setq gnus-select-method '(nntp "news")).

I haven't had time to checkout previous versions of Emacs to try and
establish when this bug was introduced.  Rather than postponing a more
useful report indefinitely, I've decided to submit this report as-is
in case someone else can try to reproduce it.


In GNU Emacs 22.0.50.1 (i386-mingw-nt5.1.2600)
 of 2006-10-14 on FILTH
X server distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.2)'

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: ENG
  locale-coding-system: cp1252
  default-enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  eldoc-mode: t
  show-paren-mode: t
  delete-selection-mode: t
  encoded-kbd-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<mouse-2> <wheel-down> <double-wheel-down> <triple-wheel-down> 
<triple-wheel-down> <wheel-up> <double-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <wheel-down> <double-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<wheel-up> <double-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <wheel-down> <double-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <wheel-down> 
<double-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <wheel-down> <double-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<triple-wheel-down> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <wheel-down> <double-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<triple-wheel-down> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
q <down-mouse-1> <mouse-1> C-x 5 2 <switch-frame> <switch-frame> 
<switch-frame> C-x m C-x k <return> M-x r e p o r t 
SPC e SPC SPC <return>

Recent messages:
byte-code: Beginning of buffer [4 times]
byte-code: End of buffer
byte-code: Beginning of buffer [5 times]
byte-code: End of buffer
byte-code: Beginning of buffer [7 times]
byte-code: End of buffer [6 times]
byte-code: Beginning of buffer [4 times]
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