Composer list in library browser

[raindog]

Are there just multiple tags named "Genre" in the file?

I'm not sure how technically it is written in the file.

Foobar shows one Genre field with multiple values:
     Classical; Choral

Mp3tag shows it in two way:
  - as two genre fields
  - or as one field separated by double backslashes:
        Classical\\Choral 

The last option (backslashes) are the option I'm using by editing tags with Mp3tag editor.

In the sample collection there are some files with multiple genres, e.g.:
- Butt, John & Dunedin Consort - [2014] Wolfgang Amadeus Mozart- Requiem
- Arte dei Suonatori & Dan Laurin - [2006] The Four Seasons
- Gardner, Edward & BBC Symphony Orchestra - [2013] Witold Lutoslawski- Orchestral Works Vol. 4