[Seaside] WASession subclasses + Magma

[Ramiro Diaz Trepat]

Another question regarding sessions.
I was looking at the modified Sushi Store example to use Magma.  I see
there, that the WAStore class>>#initialize has changed to this:

initialize

	| application |
	application := self registerAsApplication: 'store'.
	application configuration
		addAncestor: WAMagmaConfiguration new.

	^ application

My questions are:

1. Conceptually, what is an "ancestor" in the application configuration?
2. Why the initialization of the class is returning something,
particularly the application?
3. If I subclass a WAMagmaSession to add some extra information, for
instance the current user, in a MySession, what should be done in my
root component's #initialize method?
Should I still call the: "application addAncestor:
WAMagmaConfiguration new." and then call "application preferenceAt:
#sessionClass put: MySession" ?
I believe the WAMagmaConfiguration sets the session type to be
WAMagmaSession, so how should I use my own kind of session?