At the time of Ubuntu 10.04 “Lucid Lynx“, the Indicator Applet used for notifications in the Gnome panel’s system tray sorely lacks any configurability. While I imagine that soon enough you’ll at least be able to remove entries from it, it may be a while before it is truly user-friendly and offers a way to easily add more apps to it.

For those of us that don’t use the default email client Evolution, but instead use Mozilla’s Thunderbird, the notification area is less than useful. But there is a way to add Thunderbird to the Indicator Applet, and it only takes a few minutes.

First, you need to create a Desktop file for Indicator Applet, so enter the following into a terminal:

sudo touch /usr/share/applications/thunderbird.desktop

… then open it for editing:

sudo gedit /usr/share/applications/thunderbird.desktop

… adding the following text (if it doesn’t already exist):
[Desktop Entry]
Encoding=UTF-8
Name=Mozilla Thunderbird Mail/News
Comment=Read/Write Mail/News with Mozilla Thunderbird
GenericName=Mail Client
Exec=thunderbird %u
Terminal=false
X-MultipleArgs=false
Type=Application
Icon=thunderbird
Categories=Application;Network;Email;
MimeType=text/html;text/xml;application/xhtml+xml;application/xml;application/vnd.mozilla.xul+xml;application/rss+xml;application/rdf+xml;
StartupWMClass=Thunderbird-bin
StartupNotify=true

Note that you need to make sure you have specified the correct command next to Exec=, as for your particular version it could be something like thunderbird-3.0 %u (you can find out by right-clicking a Thunderbird launcher and choosing Properties). Once finished, save and close the file.

You now need to create another file for Thunderbird:

sudo touch /usr/share/indicators/messages/applications/thunderbird

… and open it for editing:

sudo gedit /usr/share/indicators/messages/applications/thunderbird

… adding the following line:
/usr/share/applications/thunderbird.desktop

All you need to do now is logout and back in again, and Mozilla Thunderbird Mail/News should be in the Indicator Applet’s mail menu.

If while trying to run sudo touch /usr/share/indicators/messages/applications/thunderbird you get the following error message:

touch: cannot touch `/usr/share/indicators/messages/applications/thunderbird’: No such file or directory

… it means you have uninstalled indicator-messages, so you need to reinstall it with this command:

sudo apt-get install indicator-messages

If your system tray is missing after this install, just log out and back in again, and it should be fine (you can try killall gnome-panel, but in my case the notification area was not restored until I had logged back in).