title: QDockWidget - window with no borders when floating
body: <p>Win 7, Qt 5.3</p>
  
  <p>I use a <code>QDockWidget</code> with my application. Works as intended.</p>
  
  <p>Now I hide the title bar by setting <code>setTitleBarWidget(new QWidget(this))</code> to a default constructed widget. This is the standard way according to Qt documentation. Also works, title bar is gone.</p>
  
  <p>In order to undock my widget as window, I use <code>myDockWidget-&gt;setFloating(true)</code> (in my own slot). But now, when the widget is undocked, the floating window has no longer borders (hence cannot be moved). </p>
  
  <p>If I comment out <code>setTitleBarWidget</code> , also <code>myDockWidget-&gt;setFloating(true)</code> works. So the original title bar seems to incorporate some logic. However, by looking at the source code I could not find anything special.</p>
  
  <p>Any hint what I can do to overcome the issue? </p>