Keep selected functionality for dropdowns

Imported From: http://groups.google.com/group/in-portal-dev/browse_thread/thread/d504c97de9a28080#

I propose we keep option, that is currently selected for item being edited in the dropdown at all costs. For example if we have field PermissionName with options based on permissions visible to user. This means, that different users will see different values. Goal is prevent PermissionName field value resetting for case, when he can't see value, that previous user have selected.

Here is an example:

UserA values: perm1, perm2, perm3 
UserB values: perm4, perm2, perm5

UserA selects value perm1 in field PermissionName. When UserB opens that database record, then value perm4 will be automatically selected or nothing will be selected at all (based on field settings) and after UserB saves database record actual value of field will be deleted.

After implementing UserB will see this values in this order: perm4, perm2, perm5, perm1 (selected). This way UserB can keep perm1 values selected if someone else with permissions have selected it before him.

To implement we need to add db value to possible option list in OnAfterItemLoad. One problem with that is how to get selected option name (what is displayed in dropdown) if it's not present in options list naturally.

Maybe what I've propose could be an approach to implement in development and not a feature to implement in core code.