[Feature Request] Transient scrollbars from kvantum

[testlab833]

Would be nice to have transient scrollbars like on Kvantum. QT apps have a ton a resizable panes and you end up with scrollbars everywhere which takes away space from content and looks a little unsightly.

[Bali10050]

89af780 adds the option for transient scrollbars based on the code of the Brise theme