页面导航如何实现A B两个页面叠层

import window from '@ohos.window'; 
 
@Entry 
@Component 
struct Page2 { 
  @State message: string = 'page Page2'; 
 
  onPageHide() { 
    console.log("pageHide") 
  } 
 
  build() { 
    Row() { 
      Column() { 
        Text(this.message) 
          .fontSize(50) 
          .fontWeight(FontWeight.Bold) 
        Button("pageB").onClick(() => { 
          let windowStege: window.WindowStage = AppStorage.get("windowStage") as window.WindowStage; 
          windowStege.createSubWindow("hello", (err, win) => { 
            // 加载页面 
            win.setUIContent('pages/Index'); 
            // 显示页面 
            win.showWindow(); 
          }) 
        }) 
      } 
      .width('100%') 
    } 
    .height('100%') 
    .backgroundColor(Color.Pink) 
  } 
}

aboutToAppear() { 
  // 页面加载的时候将子窗口透明 
  window.findWindow("hello").setWindowBackgroundColor("#00000000") 
} 
 
onBackPress() { 
  // 返回关闭子窗口 
  window.findWindow("hello").destroyWindow().then((res) => { 
    console.log("destroyWindow success") 
  }).catch(() => { 
    console.log("destroyWindow fail") 
  }) 
  return true 
}