GNOME Panel menus close unexpectedly on specific mouse clicks

Binary package hint: gnome-panel

When traversing down a Panel menu, the mouse selects the item under the mouse. When traversing up the menu, there is a sort of dead area in which the item under the mouse is NOT selected. For launchers, this is merely a cosmetic error, of one pixel: for folders on the menu, the gap has an additional pixel if the mouse is moved perfectly vertical: if the mouse is quickly clicked on that second, higher, pixel, the menu will disappear! If the mouse remains on the second pixel for a few moments without clicking, or if it is moved horizontally, the selection seems to catch up to the mouse, and there is no problem if you then click.

I found this error in regular use of the menus, however, so it's certainly not arcane! It was rather disconcerting to have my menus close on me for no apparent reason!

I cannot seem to take screenshots that contain the mouse, so I've not provided one.

ProblemType: Bug
Architecture: i386
Date: Sun Aug 5 15:54:00 2007
DistroRelease: Ubuntu 7.04
ExecutablePath: /usr/bin/gnome-panel
Package: gnome-panel 1:2.18.1-0ubuntu3.1
PackageArchitecture: i386
ProcCmdline: gnome-panel --sm-client-id default1
ProcCwd: /home/scott
ProcEnviron:
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-panel
Uname: Linux montreal 2.6.20-15-generic #2 SMP Sun Apr 15 07:36:31 UTC 2007 i686 GNU/Linux