title: When using visible binding, how do I show a message when nothing should be visible
body: <p>Imagine the following scenario.  I have a checkbox that the user can check to filter a  list based on whether they would like to see everyone, or just those persons who are managers.  Here is the simplified code:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;input type="checkbox" id="manager-view-toggle" data-bind="checked: onlyViewManagers" /&gt;
  &lt;ul data-bind="foreach: persons"&gt;
      &lt;li data-bind="visible: isManager() || !$parent.onlyViewManagers() , text: name"&gt;&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>How would I present a message to the user when no persons are visible?  I can't simply do a check on the length of persons as it could well be above 0 but there might be no managers in the list.</p>
  
  <p>I thought about using afterRender but that only fires when the content of the list changes (it seems).</p>
  
  <p>Basically, if no persons were rendered, I would like a little <code>&lt;li&gt;</code> that said something like, "No people here bro".</p>