watch for settings changes from child

def watch_thread(self):
        '''watch for settings changes from child'''
        from mp_settings import MPSetting
        while True:
            setting = self.child_pipe.recv()
            if not isinstance(setting, MPSetting):
                break
            try:
                self.settings.set(setting.name, setting.value)
            except Exception:
                print("Unable to set %s to %s" % (setting.name, setting.value))