With MPX, a second pointer entering a gtk menu prevents selecting items on the menu

[Erik B. Andersen]

With two mouse pointers via MPX, if you open a menu with one cursor and another cursor is in the menu area, neither pointer can select anything on the menu until it is reopened with only one mouse cursor in the menu area.

To reproduce:
Using Ubuntu 10.04 and having set up MPX (there's a tutorial at https://wiki.ubuntu.com/X/MPX) ,
Move the second mouse cursor to the area the Applications menu opens in.
Open the Applications menu with the first mouse cursor.
Notice that neither cursor can select any menu item.

What I would expect to happen instead:
I would either expect that the menu would allow you to select two different things, staying open until the last cursor left the menu, or I would expect what ever cursor moved last would have the highlight under it.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: libgtk2.0-0 2.20.0-0ubuntu4
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-21-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Wed May 5 18:40:20 2010
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Alpha amd64 (20100323)
ProcEnviron:
 LC_CTYPE=C
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/zsh
SourcePackage: gtk+2.0