Click and drag media items to shift their pitch?

I used to have this reaScript/custom keyboard action or SOMETHING like that: it allowed me to drag a very thin line centered inside media items, which I could click, hold and drag up or down to change pitches a half step at a time. It was the most important custom feature that I had found, hands down.

This was on another computer, on a trial version of reaper a few years ago and I cannot remember at all how I found it or even how or where it was implemented from.

I've been trying for many moons to remember what it was called or how I found it.
Please! Can anyone out there can help me figure out what this was and how I can get it back? Even if you could steer me in the right direction- maybe it was script or something else that I'm missing.