title: Non-typed ExtendedData for a gx:track in a balloon
body: <p>I am trying to attach some extended data (non typed) to a gx:track (finally, inside a gx:multitrack)
  such that if I click a track, i'd like to see a balloon with the text I put. </p>
  
  <p>UPD Note: I need different data for different tracks inside a multitrack (which is inside a placemark), i.e.:</p>
  
  <pre><code>&lt;Placemark&gt;
      &lt;name&gt;2010-05-28T01:16:35.000Z&lt;/name&gt;
      &lt;gx:Track&gt;
          &lt;when&gt;2010-05-28T02:02:09Z&lt;/when&gt;
          &lt;when&gt;2010-05-28T02:02:35Z&lt;/when&gt;
          &lt;when&gt;2010-05-28T02:02:44Z&lt;/when&gt;
          &lt;gx:coord&gt;-122.207881 37.371915 156.000000&lt;/gx:coord&gt;
          &lt;gx:coord&gt;-122.205712 37.373288 152.000000&lt;/gx:coord&gt;
          &lt;gx:coord&gt;-122.204678 37.373939 147.000000&lt;/gx:coord&gt;
          &lt;ExtendedData&gt;
              &lt;Data name="number"&gt;
                  &lt;displayName&gt;Some number&lt;/displayName&gt;
                  &lt;value&gt;1&lt;/value&gt;
              &lt;/Data&gt;
              &lt;Data name="desc"&gt;
                  &lt;displayName&gt;Some string&lt;/displayName&gt;
                  &lt;value&gt;abc&lt;/value&gt;
              &lt;/Data&gt;
          &lt;/ExtendedData&gt;
      &lt;/gx:Track&gt;
      &lt;gx:Track&gt;
          &lt;when&gt;2010-05-28T02:02:53Z&lt;/when&gt;
          &lt;when&gt;2010-05-28T02:02:54Z&lt;/when&gt;
          &lt;when&gt;2010-05-28T02:02:55Z&lt;/when&gt;
          &lt;when&gt;2010-05-28T02:02:56Z&lt;/when&gt;
          &lt;gx:coord&gt;-122.203572 37.374630 142.199997&lt;/gx:coord&gt;
          &lt;gx:coord&gt;-122.203451 37.374706 141.800003&lt;/gx:coord&gt;
          &lt;gx:coord&gt;-122.203329 37.374780 141.199997&lt;/gx:coord&gt;
          &lt;gx:coord&gt;-122.203207 37.374857 140.199997&lt;/gx:coord&gt;
          &lt;ExtendedData&gt;
              &lt;Data name="number"&gt;
                  &lt;displayName&gt;Some number&lt;/displayName&gt;
                  &lt;value&gt;2&lt;/value&gt;
              &lt;/Data&gt;
              &lt;Data name="desc"&gt;
                  &lt;displayName&gt;Some string&lt;/displayName&gt;
                  &lt;value&gt;defghj&lt;/value&gt;
              &lt;/Data&gt;
          &lt;/ExtendedData&gt;
      &lt;/gx:Track&gt;
  &lt;/Placemark&gt;
  </code></pre>
  
  <p>But in the example the extended data I define does not appear in Google Earth. 
  How can I do it right way in kml? </p>
  
  <p>KML example with extended typed data (SchemaData) work fine, I can see the data in the evaluation profile (not what I need)</p>
  
  <p>KML example with <code>&lt;Data&gt;</code> works for placemarks.
  But I can't make work <code>&lt;Data&gt;</code> inside <code>&lt;ExtendedData&gt;</code> of <code>&lt;gx:Track&gt;</code></p>
  
  <p>I'm getting empty balloons (Google Earth 7.1.1.1871 on Linux 3.9.0.0 64 bits)
  Any ideas?
  Thanks.</p>