First they tell us to use Bing, now this
After years of using Outlook Express without any problems, I switched to Thunderbird about two years ago, in no small part because of the availability of the Lightening calendar plugin.
Now I find that the recommended upgrade to TB3 to address a significant security vulnerability will leave me without calendaring, because Lightening hasn't been upgraded to work with TB3.
(https://addons.mozilla.org/en-US/thunderbird/reviews/display/2313)
Maybe I should "upgrade" to Windows Live Mail, which now has Calendar support!