Getting focused item in Tree

I see that the Tree component has focusItem(), but I don’t see any documented way to get the ID of the focused item. I see _focusId in the properties of the component, but I think there should be a function like getFocusItem() in the prototype of the Tree component so we’re not having to access “private” member data.

I just found the Selection object for the Tree component in an example, but I don’t see it in the documentation. That functions for what I need instead of focusItem(). But then I question: what is the purpose of tree.focusItem()?

Never mind my last question. I just realized today that the TreeCollection structure also applies to Toolbars, which has the Input item type that it would make sense to have a function that sets the focus on the item.