Role without edit permissions?

["Matthias Klein" <matthias@xxxxxxxxxx>]

Hi 
I would like to create a role (e.g. "students") where each member of this
role is allowed to log into eXo but not allowed to change the layout of the
page. Is that possible? How?

Here is what I have in mind:
In my last posting I asked for message board and Wiki portlets for eXo. I
want to deploy those two portlets on eXo and make them available to
students. 
When a student comes to the site (not logged in) he should see some static
text and no Wiki or Message Board.
Then he logs in.
Then he has a little menu at the top (the default one that comes with eXo is
fine) saying "Wiki" and "Forum".
When he clicks on "Wiki", he gets the Wiki full size
When he clicks on "Forum" he gets the Forum full size
Because he is logged in, both portlets know this student by name and allow
him to create new Wiki entries or post Forum messages.
But the student is not allowed to add more or other portlets to his site or
configure containers. 

How can that be done?

Thanks

Matt