So I am having problem with displaying groups of a *.desktop file into indicator-messages. I've been trying other things and searching through the internet, but I still can't find a proper solution for it.

I'm trying to integrate Thunderbird into indicator-messages (already did this), and make a few shortcuts such as Contact and Compose Email. Taking a look at the thunderbird.desktop file in /usr/share/applications after I've removed some parts of Generic Names and other unnecessary stuffs:
Code:
[Desktop Entry]
Encoding=UTF-8
Name=Thunderbird Mail
Comment=Send and receive mail with Thunderbird
GenericName=Mail Client
Exec=thunderbird %u
Terminal=false
X-MultipleArgs=false
Type=Application
Icon=thunderbird
Categories=Application;Network;Email;
MimeType=x-scheme-handler/mailto;application/x-xpinstall;
StartupNotify=true

X-Ayatana-Desktop-Shortcuts=Compose;Contacts

[Compose Shortcut Group]
Name=Compose New Message
Exec=thunderbird mailto:
OnlyShowIn=Messaging Menu

[Contacts Shortcut Group]
Name=Contacts
Exec=thunderbird -addressbook
OnlyShowIn=Messaging Menu
My file in /usr/share/indicator/messages/applications/thunderbird contains the following:
Code:
/usr/share/applications/thunderbird.desktop
The picture of my Desktop:
screenshot.jpg

After I've done all these, it only appears the "Thunderbird Mail." I do not see the Compose and Contacts group. I appreciate it if you can help me If you're wondering if this is necessary, I would say "No." But I want to learn more, and know why it doesn't appear as the way I want :P