If you would like to add Thunderbird to the indicator applet (Envelope) please do the following:
sudo gedit /usr/share/indicators/messages/applications/thunderbird
Add the following line
/usr/share/applications/xxxxxxxxxx.desktop
xxxxxxxxxx should be changed to the command used to summon Thunderbird. For me it was thunderbird-3.0
After this you should be able to see Thunderbird when you click on the indicator applet (Envelope)
If you would like to add Thunderbird to the indicator applet (Envelope) please do the following:
sudo gedit /usr/share/ indicators/ messages/ applications/ thunderbird
Add the following line
/usr/share/ applications/ xxxxxxxxxx. desktop
xxxxxxxxxx should be changed to the command used to summon Thunderbird. For me it was thunderbird-3.0
After this you should be able to see Thunderbird when you click on the indicator applet (Envelope)