Conflict between Global menubar extension and MinimizeToTray Revived in Thunderbird

When Global menubar extension and MinimizeToTray Revived extension are enabled at the same time, minimizing Thunderbird to the tray and reopening from there causes Global menubar to disappear. Sometimes this happens the first time, sometimes it takes a few times minimizing and reopening.

Original Description:
I have installed in my Thunderbird the add-on https://addons.mozilla.org/firefox/addon/minimizetotray-revived/
This add-on allows minimize and close Thunderbird to system tray. But thunderbird-globalmenu doesn't work when Thunderbird is closed to system tray.
---
Architecture: amd64
DistroRelease: Ubuntu 11.04
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
NonfreeKernelModules: nvidia
Package: thunderbird-globalmenu 7.0.1+build1+nobinonly-0ubuntu0.11.04.1~mts1
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 3.0.0-12.20-core2 3.0.4
Tags: natty running-unity
Uname: Linux 3.0.0-12-core2 x86_64
UnreportableReason: Este no es un paquete oficial de Ubuntu
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm admin cdrom dialout lpadmin nopasswdlogin plugdev sambashare vboxusers