Рейтинг 2 из 5 звёзд

You should have the following clearly visible in the initial description for this plugin - "This version of the Provider for Google Calendar REQUIRES Sunbird/Lightning 0.8." -
Otherwise, people like me who install it will be left wondering why it doesn't work, and the uninformative message displayed is "Requires additional items'
Thanks.

Это отзыв для предыдущей версии этого дополнения (0.4). 

I guess its different when on the Thunderbird page, but if you are on the Sunbird page, then it says "Works with 0.8 - 0.8". I'll see what I can do on the Thunderbird page.

Is the display of version numbers your only gripe? Personally I don't think that justifies a 2 star rating.