[Flow] confused about sessions

[Sasky, Patrick]

Hi there,

I have some trouble to work with sessions, because I don't find 
sufficient documentation about sessions in FLOW.

I tried to set up a simple user login. Users who logged in should see 
another menubar in header as the others. So I desire a practicable 
condition for Fluid to check for a valid session.

My session-class I have designed with the Scope "session". I can start a 
session there by injecting this class into my StandardController. This 
works.

But I have to do this in every Action again and again. Is there another 
way to start the session generally for all Actions? Then I can assign a 
variable for fluid and use it for a condition.
It isn't possible to use the constructor, because it's too early and the 
class isn't initialized yet.

Thanks in advance,
Patrick