This bug report will be sent to the Bug-GNU-Emacs mailing list
and the GNU bug tracker at debbugs.gnu.org.  Please check that
the From: line contains a valid email address.  After a delay of up
to one day, you should receive an acknowledgement at that address.

Please write in English if possible, as the Emacs maintainers
usually do not have translators for other languages.

Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug.  If you can, give a recipe
starting from `emacs -Q':

I visited a file that has more lines that fit in the screen. Then using the functions
(scroll-up 1) and (scroll-down 1) defined in my .emacs file and bound to the keys
option-up_arrow and option-down_arrow I  start scrolling up/down the text making
sure that portions of the text scroll off the screen. Then I make those same portions
of text scroll back to the screen. Instead of seeing the expected lines of text I see what
looks like portions of the toolbar, one for each line of text that was scrolled off the screen
before. See the attached screen shot.

If I then resize the window, the garbled screen goes away and I can see the text just fine,
and if a try scrolling up and down it works just fine.

My version of emacs was downloaded from emacsformacosx.com.

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
For information about debugging Emacs, please read the file
/Applications/Emacs.app/Contents/Resources/etc/DEBUG.


In GNU Emacs 24.2.1 (x86_64-apple-darwin, NS apple-appkit-1038.36)
of 2012-08-27 on bob.porkrind.org
Windowing system distributor `Apple', version 10.3.1187
Configured using:
`configure '--host=x86_64-apple-darwin' '--build=i686-apple-darwin'
'--with-ns' 'build_alias=i686-apple-darwin'
'host_alias=x86_64-apple-darwin' 'CC=gcc -mmacosx-version-min=10.5''

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: nil
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default enable-multibyte-characters: t

Major mode: Java/l

Minor modes in effect:
  show-paren-mode: t
  savehist-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  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
  abbrev-mode: t

Recent input:
M-x d <backspace> C-g C-x d <return> C-n C-n C-n C-n 
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
e C-n e C-n C-n e <M-down> <M-up> <M-up> <M-up> <M-up> 
<M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-up> <M-up> <M-up> <M-up> <M-up> 
<M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> 
<M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> 
<M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> 
<M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> 
<M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> 
<M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> <M-up> 
<M-up> <M-up> <M-up> <M-up> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <M-down> <M-down> <M-down> <M-down> 
<M-down> <M-down> <escape> x e m a c s SPC SPC C-g 
<escape> x r e p <tab> C-g <escape> x d e s c SPC f 
u n <tab> <return> r e p o <tab> r t SPC e m <tab> 
SPC SPC SPC SPC SPC <return> <escape> x d e s c SPC 
f u n <tab> <return> r e p <tab> o r <tab> SPC e SPC 
m SPC b u SPC <return> <menu-bar> <help-menu> <sen
d-emacs-bug-report>

Recent messages:
Making completion list...
Quit
Making completion list...
Quit
Making completion list...
Type C-x 1 to delete the help window.
You can run the command `describe-function' with C-h f
Making completion list... [2 times]

You can run the command `describe-function' with C-h f

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
mail-prsvr mail-utils help-fns help-mode view cc-mode cc-fonts easymenu
cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs
dired regexp-opt server misterioso-theme paren savehist time-date
tooltip ediff-hook vc-hooks lisp-float-type mwheel ns-win tool-bar dnd
fontset image fringe lisp-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 loaddefs button faces cus-face files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote make-network-process ns
multi-tty emacs)