Are you talking about a Column Filter?

great app - the best I've found

I have some suggestions though:

it should have a setting to have the main list follow "now playing" automatically

right now I mapped a hotkey to do that manually: "Focus tracklist on currently playing item"

a three-part panel with genre/artist/album, like itunes used to have before Apple destroyed it

finally, how about a Linux version?

I really like the ability to show lyrics, no other app does that, except painfully