🚀 go-pugleaf

Here is some more information.  When you create a new class, you actually
use the
subclass:instanceVariableNames:classVariableNames:poolDictionaries:catagories:
message.  To create a class with multiple superclasses, you should use the
subclass:otherSupers:instanceVariableNames:classVariableNames:catagories:
message.  Both messages are defined in class Class.

Note that the contents of the class definition window is actually a piece
of Smalltalk code.  When you accept it, the code is compiled and executed,
resulting in sending one of the above messages to the superclass.  There
is a message somewhere that defines the template for defining a new class.
If you change that message then you can get a template that has a slot for
multiple superclasses.  If not, you can just edit the template until it
has the proper form.