Lightning 1.0 リリース
http://www.mozilla.org/projects/calendar/releases/lightning1.0.html
互換性 Thunderbird 8.0a1 - 8.*, SeaMonkey 2.5a1 - 2.5.*

The most notable bugfixes and new features are:

* Full offline support, when the "Cache" is enabled for a calendar
* Improve diagnostics for the ICS provider
* Fix the top startup crash. Please give Lightning another try if you previously had issues
* Some fixes for the alarm system, specifically related to snoozing and recurring events
* Allow opening events already accepted via invitation
* Fresh new UI style for all calendar views