title: PyQt4 to PyQt5: inheritance issue
body: <p>I wanted to convert <a href="https://stackoverflow.com/a/35593078/882697">this code snippet</a> to PyQt5.
  I am running into an issue that I don't understand:</p>
  
  <pre><code>from PyQt5 import QtWidgets
  import logging
  
  class QPlainTextEditLogger(logging.Handler):
      def __init__(self, parent):
          super().__init__(parent)
  
  
  class MyDialog(QtWidgets.QDialog, QPlainTextEditLogger):
      def __init__(self, parent=None):
          super().__init__()    # &lt;= Error here
  
  if (__name__ == '__main__'):
      app = None
      if (not QtWidgets.QApplication.instance()):
          app = QtWidgets.QApplication([])
      dlg = MyDialog()
      dlg.show()
      dlg.raise_()
      if (app):
          app.exec_()
  </code></pre>
  
  <p>This produces the following error:</p>
  
  <blockquote>
  <pre><code>super().__init__(parent)
  TypeError: __init__() missing 1 required positional argument: 'parent'
  </code></pre>
  </blockquote>
  
  <p>Could someone help me?</p>
  
  <p>Thanks!</p>