Nice! What you could do is return this
in most of the method in order to allow chaining. End result will be like selection.parent().next()
…
Only for navigating methods?
Yes, you can add these chaining abilities in only a few methods at first and then extend this principle to other ones if needed. As your API is quite similar to the one provided by jQuery, you can have a look at it to see which methods have this strategy.
SelectionList works in-place and on multiple selections, so it feels a bit strange to have this strategy.