Custom property: string/indexed enum-list

I often have need for a form of multiplexed selection on things like material image textures, and a string enum custom property would be a good complement.

For example instead of some choice between hair color (images) of red, blond, brown, gray or black mapping to some integer index (1 == red), it would be nice to have python-like string-case logic.

So, for the related custom property, I would like to be able to create such a custom string select (enum of string) similar to:

and the ability to get the string and index as useful alternate access methods.