Auto-Populated drop-down lists

This question has been addressed in previous posts, but I haven't seen a clear answer on whether the feature exists, or is in development, or is unavailable.

The question is whether it's possible to create user-defined lists of artists, composers, etc. in the same way that a user-defined list of genres can be set up (Tools/Options/Tag Panel/Genres). This would let me select an artist, composer, etc. from a drop-down list of predefined entries and thus maintain data integrity within my collection, instead of having to continually comb through the collection to find & correct errors (e.g. "Anita ODay" vs. Anita O'Day").

This is currently not possible, not under development and not planned. If you want to apply a default value, consider using an action Format value.