Scrolling bug on Win32

["François-Denis Gonthier" <neumann@lostwebsite.net>]

Hi,

  This is a tentative post on this mailing list.  I've spent hours looking
for reports of that bug on Internet, without success.

  This happens on NTEmacs only, with recent CVS
(http://www.crasseux.com/emacs/) and current binary version.  I think it'd
be best to describe this with a little bit of ASCII art.

  Imagine the Emacs frame, with a big text file in it:

  +-----------------------------+
  +-----------------------------+
  |                           |^|
  |            A              | |
  |- - - - - - - - - - - - - -| |
  |                           | |
  |                           | |
  |            B              | |
  |                           | |
  +---------------------------|-|

  When I use the scrollbar on the right to scroll the text, the text display
gets divided in 2.  The text in the A region scrolls normally and follows
the regular movement of the scroll bar.  The text on the B region, on the
other, stays fixed and will not redraw until the scrolling is stopped or
slowed down.

  The respective size of the A and B region varies with the speed at which I
scroll, the size of the Emacs frame and the size of the loaded text.  At
full screen (1280x1204), it gets BAD: scrolling using the up/down arrows
causes the problem.

  I would like to know:

    - Is that behavior normal?  If not, was that bug reported somewhere?  I
could not find anything.  It may be only me unable to figure out the correct
words to search.

    - Is there a solution to that, through ELisp or manual recompilation?

Thank you.

François-Denis Gonthier