If you have the code

object Underscore {
  case class B(n: Int)
  List(B(1), B(2)).sortBy(_.n) //<-- here
}

Hovering over the underscore correctly shows you the type, "x$1: Underscore.B". However, if you ctrl+click on the underscore, it just highlights the expression "_.n".
I would expect it to take you to the class definition of "B".