Rated 5 out of 5 stars

This extension allows you to launch Thunderbird's best feature independent of the email client.

The only bug I've found so far is the red line rarely shows the current time as it should.

A "wishlist" item for me would be the ability to show the mini calendar and calendar list stacked on top of each other, as in vanilla Lightning, instead of in separate tabs. I don't use the task list (I have a separate application for that), so there's a good deal of wasted space in that pane.

Also nice to see the developer actively responding to reviews.

This review is for a previous version of the add-on (0.5.3). 

Hi, thanks for the review. I don't plan to allow it in the extension itself (it's barely usable on small screens or in a non-maximized window when the tasks are also used), but you can use this as a workaround:
https://github.com/Exalm/lightbird/issues/31#issuecomment-230282831

And as for the red line, I experience that behavior in Lightning as well.