title: Validate on Blur
body: <p>I've created a JSFiddle to help demonstrate my question: <a href="http://jsfiddle.net/jeffreyrswenson/CrYWn/5/" rel="noreferrer">http://jsfiddle.net/jeffreyrswenson/CrYWn/5/</a></p>
  
  <p>Here's what I'd like to see:</p>
  
  <ul>
  <li>Messages should not appear when page loads.</li>
  <li>Messages should appear when submit button is pushed.</li>
  <li>Messages should appear after input value is changed and user leaves element. (Tabs or clicks to next field)</li>
  <li>Messages should appear after user leave an input without changing.(For example a field is required and the user tabs through the field, but doesn't enter a value.  I'd like the validation message to appear when this happens.)</li>
  </ul>
  
  <p>The first four work as I'd expect.  Is the last item possible and if so, what do I need to change to enable that behavior?</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;label&gt;First name:
  &lt;input data-bind='value: firstName' /&gt;
  &lt;/label&gt;
  &lt;br/&gt;
  &lt;label&gt;Last name:
      &lt;input data-bind='value: lastName' /&gt;
  &lt;/label&gt;
  &lt;br/&gt;
  &lt;button type="button" data-bind='click: submit'&gt;Submit&lt;/button&gt;
  &lt;br/&gt;
  &lt;span data-bind='text: errors().length'&gt;&lt;/span&gt; errors
  </code></pre>
  
  <p>ViewModel:</p>
  
  <pre><code>var viewModel = function () {
         ko.validation.configure({
             decorateElement: true,
             registerExtenders: true,
             messagesOnModified: true,
             insertMessages: true,
             parseInputAttributes: true,
             messageTemplate: null
         });
  
         this.firstName = ko.observable().extend({
             required: true
         });
         this.lastName = ko.observable().extend({
             required: true,
             pattern: {
                 message: 'Hey this doesnt match my pattern',
                 params: '^[A-Z0-9]+$'
             }
         });
  
         this.submit = function () {
             if (this.errors().length == 0) {
                 alert('Thank you.');
             } else {
                 this.errors.showAllMessages();
             }
         };
         this.errors = ko.validation.group(this);
     };
  </code></pre>