title: Value disappears from QVector
body: <p>I have the <code>QMap</code> with <code>QVector</code> inside:</p>
  
  <pre><code>QMap&lt;QString, QMap&lt;QGraphicsView*, QVector&lt;float&gt;&gt;&gt; graphs;
  </code></pre>
  
  <p>I'm trying to execute this code:</p>
  
  <pre><code>QVector&lt;float&gt;* graphValues = &amp;(graphs.values()[i - values.count()].values()[0]);
  
  graphValues-&gt;push_back(1234);
  
  qDebug() &lt;&lt; "=== Debug messages ===\r\n";
  qDebug() &lt;&lt; "i - values.count() = " &lt;&lt; i - values.count();
  qDebug() &lt;&lt; "graphValues = " &lt;&lt; graphValues;
  qDebug() &lt;&lt; "*graphValues = " &lt;&lt; *graphValues;
  qDebug() &lt;&lt; "graphs = " &lt;&lt; graphs;
  qDebug() &lt;&lt; "graphs.values()[i - values.count()].values()[0] = " &lt;&lt; graphs.values()[i - values.count()].values()[0];
  </code></pre>
  
  <p>It gives me output:</p>
  
  <pre><code>i - values.count() =  0
  graphValues =  0x2000e90
  *graphValues =  QVector(1234)
  graphs =  QMap(("tempgraph", QMap((QGraphicsView(0x1fb1920) ,  QVector() ) ) ))
  graphs.values()[i - values.count()].values()[0] =  QVector()
  </code></pre>
  
  <p>So, where is my value? Using pointer i wait for my value in <code>graphs</code>, but it disappears.</p>