title: Knockout validation beyond message display
body: <p>I am working on KnockOut validation and so far so good. I do have a question though. I have some code like the following:</p>
  
  <pre><code> shippingMethodModel.Description.extend({ required: true });
  </code></pre>
  
  <p>And that shows a validation message below BUT does it set a flag or something which I can read to disable my save button?</p>