Mouse wheel problem with multiple displays

[RGB]

I can only test this on my XP pro machine.  On that machine I've got 2
video cards.  One AGP and one PCI.  The mouse wheel only works on Emacs
frames on the boot display.  It doesn't matter which card I use for
booting the machine.  After starting Emacs the mouse wheel works but if I
drag a frame to the other display it doesn't.  If I drag it back the
wheel starts working again.  While on the secondary display any wheel
movement causes a message in the echo area.
<nil> <wheel-down> (translated from <wheel-down>) is undefined

Upon trying other things I see that this message is also displayed if the
Emacs frame with focus is on the boot display but the mouse is not within
the frame boundaries while scrolling the wheel.

I have a guess that the problem may be negative screen coordinates not
being handled correctly.  I only suspect this because my 2nd display is
normally to the left of my boot display.  I configured it to be on the
right side and the problem went away.


In GNU Emacs 21.3.50 (i386-msvc-nt5.1.2600)
of 2005-02-01 on LD1
Distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-msvc (12.00)'

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: iso-latin-1
 default-enable-multibyte-characters: t