reference / interface
knob
A round dial in a ui block that gives its number between a low and a high: speed = knob "speed" 0 1. Drag it up or to the right to turn it up, or use the arrow keys when it has focus. It starts at the low end, or at start, and keeps its value as the sketch reloads.
turns = 0ui [ turns = knob "turns" 0 10 start 3 ]draw [ for i from 1 to turns [ circle at (i * 30) 160 radius 10 ]]
How to write it
knob text low high [start number] [at number number] [width number]
Gives a number.