title: Qt: shadow around window
body: <p>I can add shadow to widget:</p>
  
  <pre><code>QGraphicsDropShadowEffect *bodyShadow = new QGraphicsDropShadowEffect;
  bodyShadow-&gt;setBlurRadius(9.0);
  bodyShadow-&gt;setColor(QColor(0, 0, 0, 160));
  bodyShadow-&gt;setOffset(4.0);
  ui-&gt;widget-&gt;setGraphicsEffect(bodyShadow);
  </code></pre>
  
  <p>But this shadow will be only at left and down. I need shadow around widget. How to add this?</p>