Lightning 2.8b1 broken with SeaMonkey 2.23

Hi,
Lightning 2.8b1 should be the version to go with SeaMonkey 2.23, but
it's broken and it doesn't work.
When you open the calendar tab the first time this is what you get:
http://imgur.com/Gc3YuT5 while if you close the tab and open it again a
second time this is what you get: http://imgur.com/TTt7mtc
The second time looks normal but it still doesn't load any calendar and
the sync calendar context menu entry is grayed out.
Can someone confirm it? Is it possible to fix it? 6 weeks of not being
able to use the calendar at all is just too much...

thanks,
Iacopo