小编Has*_*med的帖子

    showMenu(
      context: context,
      position: RelativeRect.fromLTRB(5000, appBar.preferredSize.height + statusBarHeight!, 0.0, 0.0),
      items: [
        PopupMenuItem(
          child: Text('Cancel'),
          value: 0,
          onTap: () {
            cancelDialog();
          },
        ),
      ],
    );

  cancelDialog() {
    return () {
      showDialog(
        context: context,
        builder: (BuildContext context) => OrderCancel(order!.orderId!),
      );
    };
  }

使用以前的代码无法打开cancelDialog 。但它可以通过单击另一个按钮正确打开