how to disable textboxlist from adding tags that are not in autocomplete list

Question

Hi,

i'm using jquery textboxlist plugin with autocomplete and want to:

1. allow the user to type in something, and if it shows up in the autocomplete list, then the users can select it and a tag will be added to the box.
2. if what the user typed is not in the autocomplete (suggestion) list, then the input should be ignored.

right now when the user types in something that is not in the autocomplete list, it selects a tag that is closest to what the user has typed, how do i disable this behavior?

example: auto complete list has words: party, plan when the user types: "peek", it pics up "party" and adds it to the box. I want it to ignore this input.

any ideas? thanks.