title: How to show QWidget created from a QQuickView in frameless dialog with transparent background
body: <p>I have a <code>QWidget</code> created with <code>QWidget::createWindowContainer</code> from a <code>QQuickView</code>:</p>
  
  <pre><code>QQuickView view;
  view.setSource(QUrl("./Test.qml"));
  
  QWidget *container = QWidget::createWindowContainer(&amp;view);
  </code></pre>
  
  <p>The Qml is very simple:</p>
  
  <pre><code>import QtQuick 2.0
  Rectangle {
      width: 50
      height: 50
      color: "blue"
      radius: 5
  }
  </code></pre>
  
  <p>I need a translucent frameless container to show the rectangle. Trying to show the widget in a QDialog:</p>
  
  <pre><code>QDialog dialog;
  QHBoxLayout layout;
  
  dialog.setWindowFlags(Qt::FramelessWindowHint);
  dialog.setAttribute(Qt::WA_TranslucentBackground);
  layout.addWidget(container);
  dialog.setLayout(&amp;layout);
  dialog.show();
  </code></pre>
  
  <p>i get nothing because it seems that transparency was propagated also to <code>container</code> object. If i try to add to <code>layout</code> instead of <code>container</code> widget, for example, a <code>QPushButton</code>, all works fine and only the button is showed. I need the same result with my QML widget. Where could be the problem? I'm using Qt 5.2.1</p>