code: def show_busy(self):
          
          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()
docs: Lock buttons and enable the busy cursor.