DropdownMenuItem不可点击android compose

Question

我想在我的应用程序中的 TopAppBar 下显示一个下拉菜单。

当我单击下拉菜单时，会显示列表，但当我从列表中选择项目时没有任何反应。此外，下拉菜单不会折叠。我似乎无法再点击应用程序中的任何内容。我缺少什么？

val countriesList = mutableListOf<String>("India", "USA", "Canada", "Germany","Australia")



@Composable
fun CountrySelection() {

    // State variables
    var countryName: String by remember { mutableStateOf(countriesList[0]) }
    var expanded by remember { mutableStateOf(false)}

    Box(Modifier.fillMaxWidth(),contentAlignment = Alignment.Center) {
        Row(
            Modifier
                .padding(24.dp)
                .clickable {
                    expanded = !expanded
                }
                .padding(8.dp),
            horizontalArrangement = Arrangement.Center,
            verticalAlignment = Alignment.CenterVertically
        ) { // Anchor view
            Text(text = countryName,fontSize = 18.sp,modifier = Modifier.padding(end = 8.dp)) // Country name label
            Icon(imageVector = Icons.Filled.ArrowDropDown, contentDescription = "")

            //
            DropdownMenu(expanded = expanded, onDismissRequest = {
                expanded = false
            }) {
                countriesList.forEach{ country->
                    DropdownMenuItem(onClick = {
                        expanded = false
                        countryName = country
                    }) {
                        Text(text = country)
                    }
                }
            }
        }
    }
}