Scrolling down with down arrow get stuck in a loop in some positions. 
Cursor goes down to the bottom of the screem, but then the cursor jumps 
up some lines. The page is not scrolled down as it should be. The cursor 
is stuck in this loop.

To reproduce this start with

   emacs -Q

then open the attached file (vline.el) and do

   M-x eval-buffer
   M-x vline-mode
   M-x viper
   <down-arrow>

Just hold <down-arrow> down and the bug will eventually show up. To make 
it easier to see what happens you can reduce frame height first.




In GNU Emacs 23.0.50.1 (i386-mingw-nt5.1.2600)
  of 2008-01-13 on my-pc
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --cflags -Ic:/g/include'

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

Major mode: Emacs-Lisp

Minor modes in effect:
   vline-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
   unify-8859-on-encoding-mode: t
   utf-translate-cjk-mode: t
   auto-compression-mode: t
   line-number-mode: t

Recent input:
C-x C-f v l <tab> <return> M-x e v a l - b u f f e
r <return> M-x v i p e r - m o d e <return> M-x v l
i n e - m o d e <return> <help-echo> <help-echo> <help-echo>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <help-echo> <help-echo> M-h <f10> <menu-bar>
<help-menu> <send-emacs-bug-report>

Recent messages:
Warning: no fonts matching 
`-*-opensymbol-normal-r-normal-*-12-*-*-*-c-*-iso8859-1' available [2 times]
For information about GNU Emacs and the GNU system, type C-h C-a.
Loading subst-ksc...done
Loading subst-gb2312...done
Loading subst-big5...done
Loading subst-jis...done
Loading viper...
Loading c:/Documents and Settings/Lennart Borgman/Application 
Data/.viper...done
Loading viper...done
Vline mode enabled