As per https://wiki.ubuntu.com/MozillaTeam/Bugs , I downloaded and ran the Thunderbird build from the Mozilla website. (Note the link is incorrect, and I had to dig for the 64-bit version.) I still encountered this bug even in this version..
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1234468 Title: Active window cannot receive keystrokes To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/1234468/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
