>>       However, for at least a decade, the launcher of Synaptic, in
>> Debian, has been invoking gksu. Certainly some other sysadmin commands
>> were using it also, but synaptic is the one I mostly use.
> When you launch it from the GUI, maybe, but not when launched from the CLI.

     Sure. But for me it has never worked after just su, nor with sudo. 
I'm sure you need to do some tricks to achieve that. It doesn't work out 
of the box, or maybe when you are the user who did the install and the 
installer has tricked Policykit to allow you that? Anyway Policykit is 
yet another thing I dislike.

     Didier