title: Connecting subclass signal to superclass slot
body: <p>Given a superclass that defines a slot:</p>
  
  <pre><code>class Foo(object):
  
      @pyqtSlot()
      def my_slot(self):
          print('Called my_slot')
  </code></pre>
  
  <p>Is it then possible to hook up a signal from a subclass to this?</p>
  
  <pre><code>class Bar(QWidget, Foo):
  
      def __init__(self, parent=None):
          QWidget.__init__(self, parent)
          Foo.__init__(self)
          self.combo = QComboBox()
          self.combo.currentIndexChanged[str].connect(
              self.my_slot)
  </code></pre>
  
  <p>This fails as it does not seem to look in the base classes for my_slot. Is this possible and what is the syntax to achieve it?</p>