insert script into back?

[Alex Rice]

insert script of stack "MyMainStack" into back

Somewhere I found this code snippet, without a real good explanation of 
why one would need it. Does this transcript do anything really? Doesn't 
the mainstack already catch all messages by virtue of being the main 
stack?

Alex Rice, Software Developer
Architectural Research Consultants, Inc.
alrice at swcp.com
alex_rice at arc.to