code: def _redraw(self):
          
          # Only draw when no sub application was started.
          if self._is_running and self._sub_cli is None:
              self.render_counter += 1
              self.renderer.render(self, self.layout, is_done=self.is_done)
  
              # Fire render event.
              self.on_render.fire()
docs: Render the command line again. (Not thread safe!) (From other threads,
          or if unsure, use :meth:`.CommandLineInterface.invalidate`.)