NavPathStack如何获取顶部的compont，用于支持弹窗的context

// EntryAbility.ets 
onWindowStageCreate(windowStage: window.WindowStage) { 
  ... 
  AppStorage.setOrCreate('context', this.context); 
}
// xxx.ets 
let context: common.UIAbilityContext | undefined = AppStorage.get('context'); 
let windowClass: window.Window | undefined = undefined; 
let config: window.createWindow({ 
  name: 'my_window', 
  windowType: window.WindowType.TYPE_DIALOG, 
  ctx: context 
};