@mohamedsalah Vertical tabs is welcome, but when right-clicking on a tab, instead of the last (bottom) entry being "Reopen last closed tab" - which I think is a frequently invoked feature, it's now "Use vertical tab strip". I have repeatedly triggered vertical tab strip due to muscle memory, and at first had no idea how I got there, or how to undo it.
I think moving "Use vertical tab strip" higher up, away from single-tab specific features (close, close other tabs, close tabs to the right, and reopen closed tab) would make more sense since "vertical" is about all tabs, not just one.
Anyway, glad vertical is an option. Thanks to the Opera crew who made it happen.