title: How to make a transparent window with Qt Quick 2.0
body: <p>I've already know how to make a transparent window with Qt Quick 1.0.But I started to use Qt 5.0 and Qt Quick 2.0 recently and didn't know how to do with it.</p>
  
  <p>setAttribute
  setWindowFlags
  setStyleSheet</p>
  
  <p>The functions above are removed from the QtQuick2ApplicationViewer(QQuickView).
  So I wonder whether I can make a transparent window with Qt Quick 2 or not
  (is it because that it's based on OpenGL?).</p>