Downgrade from thunderbird 3.1.10 to 3.1.9

[feystorm]

So I ended up having to downgrade thunderbird from 3.1.10 back to 3.1.9 due to a significant bug with lightning and libnotify (why the package is marked as stable, I dont know). The bug is that calendar event reminders show up completely blank. The bug has been acknowledged upstream, and should hopefully be out in the next release. In the mean time, here's how to get back to a working version.

1) In thunderbird, open your calendar, select 'events and tasks' and then export your calendar to a file. This is needed or the calendar will show up blank when going back to 3.1.9.
2) add "=mail-client/thunderbird-3.1.10" to /etc/portage/package.mask
3) emerge thunderbird
4) rm ~/.thunderbird/<PROFILE>/calendar-data/local.sqlite (you have to remove it otherwise you wont be able to reimport the file you exported)
5) start thunderbird, open your calendar, select 'events and tasks' and then import the file you exported earlier