confirmDismiss: (DismissDirection direction) async {
  return await showDialog(
    context: context,
    builder: (BuildContext context) {
      return AlertDialog(
        title: const Text("Confirm"),
        content: const Text("Are you sure you wish to delete this item?"),
        actions: [
          FlatButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: const Text("DELETE")
          ),
          FlatButton(
            onPressed: () => Navigator.of(context).pop(false),
            child: const Text("CANCEL"),
          ),
        ],
      );
    },
  );
},