improve show-scrollbar pref
Right now (modulo #8039 (closed)), setting the scrollbar pref to 'never' still shows the overlay scrollbar, unless you also set a gtk setting (gtk-overlay-scrolling
). That's not convenient, or discoverable. 'never' must mean 'no scrollbar', regardless of other gtk settings.
The pref is already an enum, and we could add another value to signify 'overlay scrollbar', and a combobox in the prefs, with "No scrollbar", "Overlay scrollbar", "(Real) Scrollbar".
Or we could separate the pref out into a "Show scrollbar" bool and a "Use overlay scrollbar" bool.