I removed Unity from my system (Ubuntu 13.04), however, there is a remaining file located in Thunderbird Extensions, which is "Messaging Menu and Unity Launcher integration". I searched for the file in Synaptic, but I didn't find it.
My question is: What is the name of the package?
/usr/lib/thunderbird-addons/extensions/. Runningsudo rm /usr/lib/thunderbird-addons/extensions/messagingmenu@mozilla.com.xpidid the trick. Thanks for your help! – Removed May 10 '13 at 05:18