If you have an outer class and an inner class:

class Outer {
  class Inner
}
object TryIt {
  val outer = new Outer
  val inner: Outer# //<--- [ctrl+space]
}

When giving a type annotation of "Outer#Inner", "Inner" is not in the autocomplete suggestions. Instead, the suggestions are full of many classes, none of which would compile if selected.
These other classes (eg "IncompatibleClassChangeError") should not show up in autocomplete, instead only "Inner" should.