title: Cause helper to react to event
body: <p>I have a template with helpers and events like:</p>
  
  <pre><code>Template.myTemplate.helpers({
    edit: function () {
      console.log('helper');
      return this.value;
    }
  });
  
  Template.myTemplate.events({
    'click .edit_button': function () {
      console.log('click');
      // Toggle the value this.value
    }
  });
  </code></pre>
  
  <p>Through the logs (simplified here) I can verify that the helper is called when the template is rendered on the page. However, when the event is fired the helper console message is not fired. It as though the event changing the value does not trigger processing of the helper, making the page not very reactive.</p>
  
  <p>I have tried to assign a reactive variable and use it, to no avail.</p>
  
  <pre><code>Template.myTemplate.rendered = function () {
    this.value = new ReactiveVar();
  }
  // Setting and getting using the .get()/.set() methods.
  </code></pre>
  
  <p>How does one cause the helpers to be reprocessed from an event?</p>