This problem appears to have been corrected in Ubuntu 14.04 and 16.05. This ticket can be closed. Thank you.
** Changed in: thunderbird (Ubuntu) Status: Incomplete => Fix Released -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1002424 Title: After upgrading to Precise (12.04), Lightning calendar tab always disappears on Thunderbird restart To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/1002424/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs