Great! My only complain is, tabs previews are not showing in the order as Ctrl-Tab, where tabs are arranged according to their recent activation, which would be a lot more convenient.

This plugin may not be able to see tabs which have been slept or discarded by Firefox or other plugins. It works amazingly well with a bunch of tabs, provided you don't have them slept or discarded, though. Thanks!

Shows thumbnails for only 4 tabs

可以