The menu will scroll to the top of the option group instead of to the focused item. This means that sometimes (a.k.a. always with more than about 5 items) the focused item will not be visible, which is not desirable at all. See this plknr: https://embed.plnkr.co/4NgjYpGQ3xh4YBEtUYEd/
This issue is directly caused by #17 (af040a6).