reference / interface
toggle
A check box in a ui block that is true while it is ticked: trails = toggle "trails". It starts off, or as start says, and keeps its value as the sketch reloads.
big = falseui [ big = toggle "big" ]draw [ if big [ circle at 200 150 radius 80 ] else [ circle at 200 150 radius 40 ]]
How to write it
toggle text [start true or false] [at number number] [width number]
Gives true or false.