Title more or less says it all. I don't mean mute the tracks but lower the volume on non-active tracks.
 
I might be dreaming but I thought I read about this in the Reference manual but if it is a feature I'm not sure what it's call so I can't look it up.

Dim Solo

Any relation to Hans Solo?

Thanks. I just looked it up. Page 200 in the Reference Manual.

No not really though some say there is a family resemblance.

If you looked up Dim Solo also look up Exclusive Solo too. Very useful. 

Thanks John.

I'll check out the Exclusive Solo as well.

There are just too many options.

What happens is one gets settled into doing something one way and that's the way it stays.

Dim Solo & Exclusive Solo are great features - I use them all the time when mixing.

But to permanently lower the volumes of tracks, just select which tracks you want lowered using the ctrl key, then with ctrl still pressed, lower the fader on any one of the selected tracks, and the rest will drop proportionally to whatever you set with your selected track.