regarding User Management, Control Center & Vala

Hello everyone,

Is it possible for the gnome-user-accounts panel to manage user roles? I
mean allowing users to define roles and assign specific permissions to
those roles (preferably based on PolicyKit).

I've been recently giving some thought to develop an application to
accomplish this, which has led me to some questions:

1st: At least on Ubuntu (with Gnome 3.2) the user configuration tool
included within Gnome-Control-Center allows only to user roles: Standard
and Administrator. Is it possible to define others? Is this Ubuntu or
Gnome limitation? If I could include user profiles management in the
Gnome-Control-Center then I wouldn't need to develop a new utility but
only to extend the existing one. 

2nd: In the case that it is not possible to add custom user roles on the
existing control-center panel, is it possible to embed an external
application within the control-center, achieving a behaviour similar as
that of the default panels? That is opening within the control-center
window, rather than a separate one?

3rd: L[e]ast of all, a curiosity: why is it that Vala is recommended by
the Gnome Team as programming language for the Gnome Platform, yet every
official tool is developed in C??

Best regards,
--

-- 

                                                         Sw.E. D.H. Bahr
                                         Nova Desktop Development Leader
                                      CESOL (Free/Libre Software Centre)
                                UCI (University of Informatics Sciences)
                                                            Havana, Cuba

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