Rated 5 out of 5 stars

le Escuincle ar Iúil 5, 2010 · buan-nasc

... confirming larry54's problem.
I can't use the add-on with TB 3.1 either. Klicking the options button in the add-on window freezes it up. The signature switch icon can't be added to the compose window toolbar because it doesn't show up in the "customize toolbar" window.
I'd be more than happy for any kind of fix/update/workaround.