>>Or it could be a class which restores default settings in its Destroy. This is how it's implemented in Mere Mortals framework.
>
>session Destroy ?

Knowing CodeBook oriented frameworks, that would be some cSet class, which gets a setting, stores the old setting as a property, sets the new setting - all in .init, and when destroyed, restores the original setting. You need to create one such object for each setting you want to be non-default. The nice thing is that it contains its own cleanup code. You just declare it as local.