How to model a to-do application

Hello Vaadin users,

I’ve seen
this presentation of AngularJS
, and wanted to try to accomplish something similar in Vaadin.

It consists of a to-do application. Each row has a checkbox and a description. You can add tasks, check them as completed, un-check them, etc.

Take for example the amount of (completed) items. What is the best way to bind a label to such a calculation?

Thanks in advance,

Sebastian