Haven't we seen this before? (Score 1)

I seem to recall a very small roller-controller that fit on your index finger, and was rolled by your thumb. I want to call it a Thumbelina (but maybe I'm just making that up), and I remember seeing on in use (step-sister's laptop) back in the days of the 486. Wonder what they've done with it over the last 20 years other than make it optical.