• check option, which can allow you to specify a function to filter out new boxes that do not meet a requirement
• encode now receives the complete values, not only the id or string of the bit. This gives you full control of what you want to send to the server.

• Autocomplete now works with on-demand suggestions. As easy as this:

  new TextboxList('form_tags_input_4', {unique: true, plugins: {autocomplete: {
  	minLength: 3,
  	queryRemote: true,
  	remote: {url: 'autocomplete2.php'}
  }}});
  

And some bugfixes:

• Fixed missing index when unique: false and autocomplete were used, which resulted in an error
• Fixed problems with items with id 0, which incorrectly evaluated as false.

Head to the demo to see the new autocomplete in action, and as usual, report any bugs you might encounter.
Update: 0.5 is out already, which fixes a bug with the traditional use of Autocomplete. Sorry for the trouble!