Comment 1 for bug 1196216

Glad I found this. Problem solved. Only I'm running Mint 16 (based on Ubunty saucy), and the plugin I needed to disable is called "Messaging Menu and Unity Launcher Integration 1.3.1".

I'd had that disabled before, but had deleted some files in my thunderbird profile when recovering from a nasty crash, and it seems my preferences for which add-ons should be enabled had been forgotten. I'd like to remove that plugin from my system entirely, but am not clear what module installed it.