def splashScreen(self):
      img = QLabel(self.w)
      img.setGeometry(0,0,640,480)
      pixmap = QPixmap('background.png')
      img.setPixmap(pixmap.scaled(640,480,Qt.KeepAspectRatio))
      QTimer.singleShot(2000, img.hide)

   def mainScreen(self):
      btn=QPushButton(self.w)
      btn.setText('Click')
      btn.move(270,228)
      btn.setCursor(QCursor(Qt.PointingHandCursor))

   def run(self):
      self.mainScreen()   # --> paint the button
      self.splashScreen() # --> paint the img on top layer
      self.w.show()       # --> display the widget