This is a good start to implement mouse gestures with WebExtensions in Firefox, but it's still a little basic.
My biggest annoyance is that restored tabs get loaded just with their last URL, not with their full tab history. Also you can't customize any gestures, like up/down.

Не хватает индикации событий (как было в Опере Presto)
Можно ли реализовать быстрый переход по открытым вкладкам?

The only gestures ad-don really lite on resources.
Will be great to add in future more gestures movements.
Doesn't work on internal pages like about:support.
Thanks.