title: Read session variable without invalidating context
body: <p>Is there a way to read from a Session variable without re-rendering the template when it changes?</p>
  
  <p>The scenario:</p>
  
  <p>I change the style of elements dynamically using jQuery, but when a new element is created I want to set its default style (I know I could call the same jQuery command when the element is rendered)</p>
  
  <p><strong>Example:</strong></p>
  
  <pre><code>&lt;template name="image"&gt;
      &lt;!-- How can I avoid -height- being reactive --&gt;
      &lt;img src="img.jpg" style="height: {{height}}"&gt;
  &lt;/template&gt;
  
  Templates.image.height = function() {
      return Session.get("height");
  };
  
  Templates.controls.events = {
      'click #btn': function() {
          // Change the height of all exiting images
          $("img").css({height: Session.get("height")});
      }
  };
  </code></pre>
  
  <p>I would like every new image added to have the height stored in the session variable without re-rendering the <code>img</code>. All the solutions I can think of feel like hacks.</p>