title: PyQt write inherit from QWidget
body: <p>I'm about to refactor a messy code of a small GUI and tried combine a few elements into a new class which inherits from QWidget. Sadly, the widget isn't painted, but doesn't produce an error either.</p>
  
  <p>A made a minimal example of the problem:</p>
  
  <pre><code>from PyQt5.QtWidgets import QWidget, QVBoxLayout, QLabel
  
  
  class ExportOptions(QWidget):
      def __int__(self, parent=None):
          QWidget.__init__(self, parent)
          self.mainLayout = QVBoxLayout(self)
          #self.setFixedSize(100,100)
          self.mainLayout.addWidget(QLabel("Test"))
          self.setLayout(self.mainLayout)
          self.show()
  
  if __name__ == '__main__':
      from PyQt5.QtWidgets import QMainWindow, QApplication
      import sys
      app = QApplication(sys.argv)
      mainWindow = QMainWindow()
      mainWindow.setCentralWidget(ExportOptions())
      mainWindow.show()
      sys.exit(app.exec_())
  </code></pre>
  
  <p>Running the file produces an empty window without the Label.
  I think I'm missing something very trivial, but I can't spot it...</p>
  
  <p>I'm using latest <code>Anaconda2 i.e.</code> <code>Python 2.7</code> and <code>pyQt 5.8</code> on a windows machine.
  Thanks for the help!</p>