Review unsubscribe group list in CiviMail

At Present Users are able to send an bulk email to a "Smart" Group and then if someone clicks on an unsubsubscribe link they are unsubscribed from the "Smart" group which ensures that they are excluded from the mailing. However if you go to create a bulk mail from the mass mailing action link on advanced search, there is a box to specify which group should be used as the unsubscribe group which contains only non-smart or static groups. Given some of my users need to create 1 list from various different groups they use the 1 smart group and they would like to be able to select the smart group as the unsubscribe group.

The fact that the unsubscribe group only lists static group also doesn't seem to match functionality else where.

Further the static group listing does not respect ACLs so in a multisite setup all domains groups are shown to acled users.

I think the sensible option would be to align this to the rest of the CIviMailing system and used the NestedGroups: mailing system to generate the list of mailing groups.