title: kendo: Enable / Disable button in navigation bar
body: <p>Below is a definition of the navigation bar, part of a view template that is used among several screens:</p>
  
  <pre><code>    &lt;div data-role="layout" data-id="app"&gt;
          &lt;header data-role="header"&gt;
            &lt;div data-role="navbar"&gt;
                &lt;a class="nav-button" data-align="left" data-role="backbutton"&gt;Back&lt;/a&gt; 
                &lt;span data-role="view-title"&gt;Title&lt;/span&gt;
                &lt;a class="nav-button" data-align="right" data-role="button" data-click="doneTapped" id="btnDone"&gt;Done&lt;/a&gt; 
            &lt;/div&gt;
          &lt;/header&gt;
      &lt;/div&gt;
  </code></pre>
  
  <p>The "Done" button is only needed on some screens, so it gets hidden when the main page loads:</p>
  
  <pre><code>    $("#btnDone").hide();
  </code></pre>
  
  <p>Hiding the button works fine, but showing it again does not work:</p>
  
  <pre><code>    $("#btnDone").show();
  </code></pre>
  
  <p>The button does not show up.</p>