You're extension was really great. I'm happy that you still work on it.
However, I notice some problem. Try to add an element, remove it, add again.
The available selection grows... but with duplicate items.
The link to the demo doesn't work.
Finally, I agree with galdaka suggestion and could be good to have a reset function which remove boxes (caption and on the store) and free-element.
Even if you don't want to add this functionnality, could explain me how to get and to remove the RawValue properly.