Haiku has stackable tabs instead of title bars.[1] KDE used to let you group windows as tabs.[2] Microsoft experimented with it.[3] [1] https://www.haiku-os.or

Haiku has stackable tabs instead of title bars.[1] KDE used to let you group windows as tabs.[2] Microsoft experimented with it.[3] [1] https://www.haiku-os.org/docs/userguide/en/gui.html#stack-tile https://www.haiku-os.org/docs/userguide/en/gui.html#stack-ti... [2] https://superuser.com/questions/848840/triggering-kdes-attach-as-tab-to-feature-from-a-shell-script https://superuser.com/questions/848840/triggering-kdes-attac... [3] https://www.zdnet.com/article/windows-10s-sets-feature-is-gone-and-not-expected-to-return/ https://www.zdnet.com/article/windows-10s-sets-feature-is-go...