def show_busy(self):
        """Lock buttons and enable the busy cursor."""
        self.progress_bar.show()
        self.parent.pbnNext.setEnabled(False)
        self.parent.pbnBack.setEnabled(False)
        self.parent.pbnCancel.setEnabled(False)
        self.parent.repaint()
        enable_busy_cursor()
        QgsApplication.processEvents()