Guys,
I really hope this is not caring over to 10.x.
When defining basic functions to manipulate settings (add/change/remove) some common sense and validations are required.
The issue here is the change function: When changing setting, the function should open a windows with the fields as previously stored and allow change, validate at exit, etc. Should not make changes to the previously stored values as it is happening with the jail configuration in 9.10.
Open for discussion on programming philosophy.