[Evolution-hackers] mail lockdown

[Not Zed <notzed ximian com>]

after much pain we worked out some of the gconf stuff and i did some
testing.  the code is now committed.

anyway here's a summary of the account lockdown settings.  someone else
needs to review this to see if it provides enough functionality and/or
what behavioural changes need to be implemented, and further specify
them in detail.

note it doesn't really cover the stuff which is locked by gconf
mechanisms.  we just support honouring (at least in the ui) locking of
every key for all mail prefs so that's basically done as can be.

 michael
---

Mailer lockdown.

Most settings are set via locking the gconf keys.  This includes "all
accounts" and "all signatures" lockdown settings.  Individual fields
within accounts are locked down separately, using a set of lockdown
keys.

Lockdown keys

Currently, the keys are all bool's and live in gconf under
`/apps/evolution/lock/mail/accounts'.  This can be easily moved, i
haven't written a schema file yet, nor am i in any rush to.

These lockdown settings merely prevent the setting from being changed.
To provide values, the gconf defaults mechamism needs to be used.  But
that can only, for example, provide 'n' fully populated accounts, it
can't provide defaults for a 'new account'.

imap_subscribed
	Lock the imap "use subscribed folders only" setting.

imap_namespace
	Lock the namespace setting.

filter_inbox
	Lock whether the source account has filtering applied to the
	inbox.  This currently only applies to IMAP.

filter_junk
	Lock whether junk filtering is applied or not to this store.
	This currently only applies to IMAP.

ssl
	Lock whether the "use ssl" option can be changed (source or
destination).

signature
	Lock the per-account signature setting from being changed.

authtype
	Lock the authentication type option.

autocheck
	Lock both the autocheck enable and autocheck time value.

default_folders
	Lock the default folders from being changed.

save_passwd
	Lock the setting on the account as to whether the password is
	saved or not.  The password dialogue probably needs to honour
	this too.

source
	Lock everything to do with the mail source (mail receiving and
	mail receiving options tab).  This implicitly activates most
	of the settings above.

transport
	Lock everything to do with the mail transport (mail sending
	tab).

In addition, if the accounts key is readonly, then now account settings
cannot be altered in any way (or even viewed).

There is some inconsistency, in that if you lock down certain options
which are required for setting up a new account, but you don't lock
down all accounts, then you may be able to attempt to add an account,
but not be able to succeed in adding the account.  There is no direct
mechamism using gconf to provide defaults for any options locked in
this manner (as hinted to above).