@kolya @kevinrns with no uniform naming of the "grouping of tabs" feature it's card to use a generic term… (and stacked tabs was initially an opera term if my memory is not failing me).
By the way I'm a firefox, chrome and vivaldi user but yes mainly vivaldi for the moment (I'm waiting for a tab grouping/stacking/whatever equivalent to land in firefox to come back to my beloved mozilla flavored browser !
@pmartin @kevinrns
Vivaldi's unique implementation of stacked tabs (which preceded Chrome's tab groups) was one of the things that made me leave Vivaldi, because it basically doesn't support drag+drop which is what I use extensively. That's why I instantly recognized your use of the term. No offense meant. :)