title: Tabify 3 QDockWidget
body: <p>How can I create a tabified dock for 3 widgets in QMainWindow?</p>
  
  <p>I'm using the code bellow:</p>
  
  <pre><code>widget1 = new QDockWidget(this);
  widget1 -&gt;setObjectName("name1");
  addDockWidget(Qt::LeftDockWidgetArea, widget1);
  widget2 = new QDockWidget(this);
  widget2 -&gt;setObjectName("name2");
  addDockWidget(Qt::LeftDockWidgetArea, widget2);
  tabifyDockWidget(widget2, widget1);
  widget3 = new QDockWidget(this);
  widget3-&gt;setObjectName("name3");
  addDockWidget(Qt::LeftDockWidgetArea, widget3);
  tabifyDockWidget(widget3, widget1);
  </code></pre>
  
  <p>This code is resulting in two docks: Dock 2 alone, and Dock 1 and 3 tabified.</p>