Last updated at 1:09 am UTC on 17 February 2017
Since Squeak version 2.5 there is no WorldMorph class anymore.
An instance of WorldMorph was the topmost morph which contained all other Morph instances. It kept a list of morphs which need stepping and sent them a stepping message when the scheduled time had come.
Nowadays a PasteUpMorph, named World, is used instead of a WorldMorph. With the message isWorldMorph you can check if a Morph is designated a World. Multiple Worlds are possible in an Image, each Project in an image will have its own World.
See now PasteUpMorph.
Noteworthy is that in Pharo Smalltalk the WorldMorph was reintroduced again.
PasteUpMorph subclass: #WorldMorph
instanceVariableNames: 'osWindow session'