An in-depth help page with examples can be found here. and a help area is at Code Island
A Happening can be used to create visuals lasting up to 15 seconds. It has two sub-types (Brain and Changer), and all three types are made using JavaScript. You can no longer create new Happenings, Brains, or Changers.
Happenings can be used as personal Boosts and can also be walked over in areas.
Brain[]
An in-depth help page can be found here.
Brains can be equipped on the player to make them say certain things, do certain things, and more. They cannot be placed in open edits areas.
Changer[]
An in-depth help page can be found here.
Changers affect creations. With changers you can shrink, enlarge, change the colour of, clear the unused palette of a creation, and more. Changers can be used by dragging and dropping a creation on them to produce the new creation.