code: def start_refresh(self):
          
          self.logger.debug("starting timed refresh interval")
          self.rf_flags['done'] = False
          self.rf_draw_count = 0
          self.rf_timer_count = 0
          self.rf_late_count = 0
          self.rf_late_total = 0.0
          self.rf_early_count = 0
          self.rf_early_total = 0.0
          self.rf_delta_total = 0.0
          self.rf_skip_total = 0.0
          self.rf_start_time = time.time()
          self.rf_deadline = self.rf_start_time
          self.refresh_timer_cb(self.rf_timer, self.rf_flags)
docs: Start redrawing the canvas at the previously set timed interval.