Hi,

After resizing the window in longlines mode, the buffer sometimes
appears to be modified. I've attached a simple example with which
I can reproduce the bug on at least two machines (Debian with
emacs-snapshot 20070701-1 and Mac OS X with GNU Emacs 22.0.97.1).

1. Open the file with
  emacs -q -eval '(setq longlines-wrap-follows-window-size t)' file.html
   (The mode should be XHTML.)
2. Activate the longlines mode (ESC x longlines-mode RET).
3. Extend the window to 81 columns.
4. Hit the down arrow.

I couldn't reproduce the problem in fundamental mode, but I have
the same problem in nXML mode, but on a more complex example
(which I haven't tried to simplify).

-- 
Vincent Lefèvre <vincent@vinc17.org> - Web: <http://www.vinc17.org/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/>
Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon)