docs: def meta_changed(self, model, prop_name, info):
          """When the meta was changed, we have to set the dirty flag, as the changes are unsaved"""
          self.state_machine.marked_dirty = True
          msg = info.arg
          if model is not self and msg.change.startswith('sm_notification_'):  # Signal was caused by the root state
              # Emit state_meta_signal to inform observing controllers about changes made to the meta data within the
              # state machine
              # -> removes mark of "sm_notification_"-prepend to mark root-state msg forwarded to state machine label
              msg = msg._replace(change=msg.change.replace('sm_notification_', '', 1))
              self.state_meta_signal.emit(msg)