How to use the feeluown.controller_api.ControllerApi.notify_widget function in feeluown

def exit(cls):
        ControllerApi.notify_widget.show_message("通知", "退出单曲电台播放模式")

def play_mv_by_mvid(cls, mvid):
        mv_model = ControllerApi.api.get_mv_detail(mvid)
        if not ControllerApi.api.is_response_ok(mv_model):
            return

        url_middle = mv_model['url_middle']
        clipboard = QApplication.clipboard()
        clipboard.setText(url_middle)

        cls.view.ui.STATUS_BAR.showMessage(
                u"程序已经将视频的播放地址复制到剪切板", 5000)
        if platform.system() == "Linux":
            ControllerApi.player.pause()
            ControllerApi.notify_widget.show_message(
                    "通知", "正在尝试调用VLC视频播放器播放MV")
            try:
                subprocess.Popen(['vlc', url_middle, '--play-and-exit', '-f'])
            except:
                LOG.error('call vlc player failed')
        elif platform.system().lower() == 'Darwin'.lower():
            ControllerApi.player.pause()
            ControllerApi.notify_widget.show_message(
                    "通知", "准备调用 QuickTime Player 播放mv")
            try:
                subprocess.Popen(
                    ['open', '-a', 'QuickTime Player', url_middle])
            except:
                LOG.error('call quicktime player failed')

def delete_playlist(self):
        m = QMessageBox(QMessageBox.Warning, '警告', '确认删除歌单么 ?',
                        QMessageBox.Yes | QMessageBox.No)
        if m.exec() != QMessageBox.Yes:
            return False

        pid = self.data['id']
        flag = ControllerApi.api.delete_playlist(pid)
        if flag:
            ControllerApi.notify_widget.show_message('◕◡◔', '删除歌单成功')
            self.close()
            self.deleteLater()
            return True
        else:
            ControllerApi.notify_widget.show_message('◕◠◔', '删除歌单失败')
            return False

def add_to_playlist(self, pid):
        if not ControllerApi.state['current_mid']:
            return False
        flag = ControllerApi.api.add_song_to_playlist(ControllerApi.state['current_mid'], pid)
        if flag:
            ControllerApi.notify_widget.show_message('◕◡◔', '加入歌单成功')
        else:
            ControllerApi.notify_widget.show_message('◕◠◔', '加入歌单失败, 可能早已在列表了哦')

LOG.info('正在查找新版本...')
        try:
            loop = asyncio.get_event_loop()
            future = loop.run_in_executor(
                    None, partial(requests.get, url, timeout=5))
            res = yield from future
            if not res.status_code == 200:
                LOG.warning('connect to api.github.com timeout')
                return
            releases = res.json()
            for release in releases:
                if release['tag_name'] > cls.current_version:
                    title = u'发现新版本 %s hoho' % release['tag_name']
                    LOG.info(title)
                    content = release['name']
                    ControllerApi.notify_widget.show_message(title, content)
                    ViewOp.ui.STATUS_BAR.showMessage(title, 5000)
                    break
        except Exception as e:
            LOG.error(str(e))

def show_start_tip():
        tips_content = list(tips.values())
        index = random.randint(0, len(tips_content)-1)
        ControllerApi.notify_widget.show_message("Tips", tips_content[index])