To complement his ideas,
PolicyKit allows you to map actions like
this way you can separate the privileged code,
you can detect which "tab" the user is and
when "apply" is called "org.kde.kdm.background"
can be issued to get an authorization.
Note that mapping is a nice feature but
making too many actions adds more compressibility
to your code.
Also i'd like to say that we are willing to help
date & time and login manager kcm's to get
integrated with polkit. (of course if there are others
they can ask us for help too)
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