title: Assigning to nested QVariantMap
body: <pre><code>#include &lt;QtCore/QCoreApplication&gt;
  #include &lt;QVariant&gt;
  #include &lt;QtDebug&gt;
  
  int main(int argc, char *argv[])
  {
      QCoreApplication a(argc, argv);
      QVariantMap map;
      map["foo"] = QVariant(QVariantMap());
      map["baz"] = "asdf";
      qvariant_cast&lt;QVariantMap&gt;(map["foo"])["bar"] = "a";
  
      qDebug() &lt;&lt; qvariant_cast&lt;QVariantMap&gt;(map["foo"])["bar"].toString();
      qDebug() &lt;&lt; map["baz"].toString();
  
      return a.exec();
  }
  </code></pre>
  
  <p>I am trying to assign to a QVariant within a nested QVariantMap.  The first qDebug() outputs nothing, but the second outputs "asdf" as expected.  How would I assign the "bar" key in the nested variable map to a value?</p>