For a group indicator, don't forget that a track can belong to multiple groups. Thus my vote is for an indicator, which by a right click will bring up information about the grouping.
__________________ Reaper for Linux Documentation (WIP). Software: Archlinux/KDE, Fabfilter FX, Komplete 8, Nebula, Schwa/Stillwell, T-racks Max/Amplitube/SVX, etc. Gear: i7-2600k/4700HQ/16GB, RME Multiface/Babyface, Behringer X32, Genelec 8040, etc. :)
Linear Mode
