Setting preferences as not changeable -- changeable bit?

[Michael Bull]

Hi all,
I'd like to set some of the preferences in 2.3 to not be changeable by the 
user (I've got a 2.3 development site up, but I'd like to lock it down a 
bit).  Unless my eyes are failing me, I didn't see any settings yet in the 
conf.php similar to the ones in default.php3 from 2.2 -- looking through 
the code, though, I notice that decisions about what to do seem to be 
related to an "IsChangeable" function; I tracked it down to Prefs.php in 
horde/lib, and in reading over it it makes mention of checking the pref in 
questions "changeable bit".

Is setting this bit what I'm after to make preferences not changeable by 
the user, and if so... what do I need to do for it to be set?  Thanks!