title: QGraphicsProxyWidget messes up mouse cursor changes
body: <p>I have a <code>QGraphicsView</code> where I do various mouse operations and while doing mouse operations I change mouse cursor to give user visual clues.</p>
  <p>I recently put some QWidgets onto my scene which automatically creates <code>QGraphicsProxyWidget</code> objects. And after putting these widgets I started having problems with my mouse cursor changes. I can change mouse cursor until I hover over a <code>QGraphicsProxyWidget</code> item. After that, my mouse cursor changes stop taking effect.</p>
  <p>I created a minimal example in PySide2:</p>
  <pre class="lang-py prettyprint-override"><code>import sys
  
  from PySide2.QtGui import QMouseEvent, Qt
  from PySide2.QtWidgets import QApplication, QLabel, QGraphicsView, QGraphicsScene
  
  
  class CustomGraphicsView(QGraphicsView):
      def mousePressEvent(self, event: QMouseEvent):
          super().mousePressEvent(event)
  
          self.setCursor(Qt.ClosedHandCursor)
          event.accept()
  
      def mouseReleaseEvent(self, event: QMouseEvent):
          super().mouseReleaseEvent(event)
  
          self.setCursor(Qt.ArrowCursor)
          event.accept()
  
  
  if __name__ == &quot;__main__&quot;:
      app = QApplication(sys.argv)
      graphics_view = CustomGraphicsView()
      scene = QGraphicsScene(0, 0, 1000, 1000)
      graphics_view.setScene(scene)
  
      label = QLabel(&quot;Hello World&quot;)
      label_font = label.font()
      label_font.setPointSize(50)
      label.setFont(label_font)
  
      label_proxy = scene.addWidget(label)
      label_proxy.setPos(400, 450)
  
      graphics_view.show()
      app.exec_()
  </code></pre>
  <p>To reproduce: first, click on anywhere in the scene without hovering your mouse over the &quot;Hello World&quot; text. You will see mouse cursor changing into a closed hand. Then hover your mouse over &quot;Hello World&quot; text and try again clicking anywhere on scene. You will see that the cursor is not changing anymore.</p>
  <p>I am not sure if this is an expected behavior or bug. What might be the reason for this behavior?</p>
  <h2>System</h2>
  <p>OS: Windows 10 20H2</p>
  <p>Python 3.8.6 64-bit</p>
  <p>PySide2 5.15.2</p>