Finally! Someone has come out with an add-on to undo the mess Mozilla created with the UI in Thunderbird 11. Rise of the Tools restores the Thunderbird UI back to what it was prior to Thunderbird 11. No restart needed, simply download and then either drag it into the Thunderbird add-ons manager or from within the Thunderbird add-ons manager click on the ‘Gear’ and select Install Add-on From File... This also works with Thunderbird 12 Beta, Earlybird 13 Alpha 2 and Thunderbird 14 Daily builds.