HarmonyOS 自定义弹窗不能显示问题

请参考示例：

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';

  build() {
    Row() {
      Column({ space: 20 }) {
        Button('Toast显示')
          .onClick(() => {
            new GlobalDialog().showDialog($r('app.media.startIcon'), 'test')

            setTimeout(()=>{
              new GlobalDialog().hide()
            },2000)
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}

@CustomDialog
struct _GlobalDialog {
  controller: CustomDialogController
  close: () => void = () => {
  }
  image: ResourceStr | undefined = undefined
  @State msg: string = ""

  build() {
    Column() {
      Text(this.msg)
        .fontColor(Color.White)
        .width(px2vp(200))
        .height(px2vp(200))

      Image(this.image)
        .fitOriginalSize(true)
        .objectFit(ImageFit.None)
    }
    .justifyContent(FlexAlign.Center)
    .alignItems(HorizontalAlign.Center)
    .padding(12)
    .margin(30)
    .backgroundColor(Color.Black)
    .borderRadius(10)
    .shadow({
      radius: 10,
      color: Color.Gray,
      offsetX: 3,
      offsetY: 0
    })
  }
}

let _dialogController: CustomDialogController | null
let _cancelCallBack: (() => void) | undefined
@Component
export struct GlobalDialog {
  showDialog(
    image: Resource | undefined,
    msg: string,
    cancelCallBack?: () => void,
    alignment: DialogAlignment = DialogAlignment.Center,
    offset: Offset = { dx: 0, dy: 0 },
    showInSubWindow: boolean = false,
    isModal: boolean = false,
  ): void {
    this.hide()
    _cancelCallBack = cancelCallBack
    let animate: AnimateParam = {
      duration: 90,
      delay: 0,
      curve: Curve.EaseInOut
    }

    _dialogController = new CustomDialogController({
      builder: _GlobalDialog({ image: image, msg: msg }),
      autoCancel: false,
      cancel: () => {
        _dialogController = null
        if (_cancelCallBack) {
          _cancelCallBack()
        }
      },
      customStyle: true,
      alignment: alignment,
      offset: offset,
      maskColor: 0x01000000,
      openAnimation: animate,
      closeAnimation: animate,
      showInSubWindow: showInSubWindow,
      isModal: isModal,
    })
    _dialogController.open()
  }

  hide() {
    if (_dialogController) {
      _dialogController.close()
      _dialogController = null
      if (_cancelCallBack) {
        _cancelCallBack()
      }
    }
  }

  build() {
  }
}