Add keywords in the .desktop file
This is, for example, needed for a good Unity integration in French.
In French you can't find Thunderbird in the Unity dash if you type "mail" because it was translated to "courriel" in the "comment" section of the .desktop .
This is the correct French translation, but some people still use the word "mail" in their daily life. So we need a way to add "mail", "e-mail" and similar as keywords in the desktop file so that they can easily find Thunderbird in the dash.
The .desktop file is already translated downstream on a strange fashion (see ) so I'm not sure if I can just submit a patch as explained here.
Note: there is the same problem in Firefox