title: Retrieving QPushButton from QWidget
body: <p>I have a QPushButton with related icon, and I add it to a scene:</p>
  
  <pre><code>QPushButton *button = new QPushButton;
  button-&gt;setIcon(QIcon(myIcon));
  buttonWidget = detail-&gt;scene()-&gt;addWidget(button);
  // buttonWidget is declared globally and is a QGraphicsProxyWidget*
  </code></pre>
  
  <p>Later on, in a different function, the <code>buttonWidget</code> is still accessible. How can I retrieve the <code>QPushButton</code> object from the <code>buttonWidget</code>? I would like to change its icon.</p>