editor-init.js

//create a box
box(10, 10, 20, 20);

//use random:
box(50, rand(100, 200), 20, 20);

//use random color:
box(160, 50, 20, 20, randomColor());

//center method for center of canvas:
box(center() - 10, center() - 10, 20, 20);

//width and height gives canvas size:
box(width() - 20, height() - 20, 20, 20);

//rect will not be connected to boxes:
rect(300, 200, 40, 40, "green");