Because there were an old bugs with UI::Toolbar#restore and UI::Toolba#show (as discussed in the topic linked above,) … I have been in the habit of using this:
toolbar.get_last_state == TB_NEVER_SHOWN ? toolbar.show : toolbar.restore
It always seemed to work as we expect, so I’ve never broke from this “habit”.
Thomas’ suggestion that UI::Toolbar#restore does what my “habitual” statement does, is still not declared in the documentation, now 6 years later.