To access Dev Mode, shift + click the Snap! logo at the top left corner of the editor and click on "Switch to dev mode." Dev Mode allows the morphs to be inspected and edited. Everywhere you right-click, a morphic context menu appears. There are extra primitives that only appear in Dev Mode.

Blocks

The extra blocks are:

console log [] @delInput @addInput :: looks

alert [ ] @delInput @addInput :: looks

save [ v] as costume named [] :: looks

play () Hz for () secs :: sound
(message :: control)
(processes :: sensing)
(stack size :: sensing)
(frames :: sensing)
(yields :: sensing)
(type of [] :: operators)
([ v] of [] :: operators)
show table @list :: list