Comment 7 for bug 1269414

I'm still not sure whether you are running the music app or just previewing the tracks. The music app has an exception that should work universally to let another app run in the foreground while it plays music in the background.

However, I haven't tried r129 as only r121 is stable. Maybe something changed recently that assumed all apps would make use of the media-hub. I'll try to upgrade to 129 and verify.