title: Qt adding drop shadow effect for QLabel using QGraphicsDropShadow
body: <p>I have to apply drop shadow for multiple QLabel in my Application. I used QGraphicsDropShadowEffect and it is working fine, if i am adding it for one QLabel. I tried applying the same Graphics effect for two QLabels.</p>
  
  <pre><code>QGraphicsDropShadowEffect* effect = new QGraphicsDropShadowEffect();
  effect-&gt;setColor(Qt::white);
  effect-&gt;setBlurRadius(0);
  effect-&gt;setXOffset(1);
  effect-&gt;setYOffset(0);
  QLabel* label = new QLabel();
  label-&gt;setText("QLabel1");
  label-&gt;setGraphicsEffect(effect);
  QLabel* label2 = new QLabel();
  label2-&gt;setText("QLabel2");
  label2-&gt;setGraphicsEffect(effect);
  </code></pre>
  
  <p>In this case,the shadow effect is applied only to label2.
  I tried creating two different QGraphicsDropShadowEffect objects and setting the QLabels with that.</p>
  
  <pre><code>QGraphicsDropShadowEffect* effect = new QGraphicsDropShadowEffect();
  effect-&gt;setColor(Qt::white);
  QLabel* label = new QLabel();
  label-&gt;setText("QLabel1");
  label-&gt;setGraphicsEffect(effect);
  QGraphicsDropShadowEffect* effect1 = new QGraphicsDropShadowEffect();
  effect1-&gt;setColor(Qt::white);
  QLabel* label2 = new QLabel();
  label2-&gt;setText("QLabel2");
  label2-&gt;setGraphicsEffect(effect1);
  </code></pre>
  
  <p>In this case, Application is crashing in QRasterPaintEngine::transformChanged() call.</p>
  
  <p>Any idea on how to fix this issue?
  I am using qt 5.3.</p>