Does this have anything to do with oss and opensuse? I get the message from thunderbird (see screenshot) when trying to install Lightning 1.7. Attempts to downgrade to Lightning 1.6 as suggested in another thread fail to work. Any ideas?
Thunderbird 15.0 uses Lightning 1.7. The one in your screenshot is Lightning 1.8 for Thunderbird 16.0 released yesterday.
Try this link.
https://addons.mozilla.org/en-US/thunderbird/addon/lightning/versions/?page=1#version-1.7