title: Qt QList does not append local Objects
body: <p>I have a understanding-problem why following code does not store any QString-Objects into my QList</p>
  
  <pre><code>QMap&lt;QString, QList&lt;QString&gt; &gt;map;
  map = QMap&lt;QString, QList&lt;QString&gt; &gt;();
  map.insert("eins", QList&lt;QString&gt;());
  QList&lt;QString&gt; listInMap = map["eins"];
  listInMap.append("test1");
  listInMap.append("test2");
  QList&lt;QString&gt; copyOfListInMap = map.value("eins");
  qDebug() &lt;&lt; copyOfListInMap.count();
  </code></pre>
  
  <p>Output: 0</p>