MUIA_Boopsi_ClassID specifies the name for the public
Boopsi class you want to create an object of. It will
only be used when MUIA_Boopsi_Class is NULL.
The public class must be in memory before you can create
an instance of it, you will have to open the required class
library by hand.
Note the string given to MUIA_Boopsi_ClassID must remain
valid until you're done with the object.