Android 对话框中的内容不可见

我已经在Compose中包装了一个Dialog，Android.然而，事情似乎并没有出现.我不确定我需要在这里做什么，才能正确地修复这个问题，让它自然地工作.因为，我计划使用inputs和其他东西，例如buttons等.

@SuppressLint("UnusedMaterial3ScaffoldPaddingParameter")
@OptIn(ExperimentalComposeUiApi::class, ExperimentalMaterial3Api::class)
@Composable
fun MyDialog(
    openDialog: Boolean,
    closeDialog: () -> Unit,
) {
    if (openDialog) {
        Dialog(
            properties = DialogProperties(usePlatformDefaultWidth = false),
            onDismissRequest = closeDialog,
            content = {
                Scaffold(
                    modifier = Modifier.fillMaxSize(),
                    topBar = {
                        SmallTopAppBar(
                            modifier = Modifier.padding(0.dp, 0.dp, 16.dp, 10.dp),
                            title = {
                                Text(
                                    text = "Add new item",
                                    style = MaterialTheme.typography.titleMedium,
                                )
                            },
                            colors = TopAppBarDefaults.smallTopAppBarColors(
                                containerColor = MaterialTheme.colorScheme.background
                            ),
                            navigationIcon = {
                                IconButton(onClick = {
                                    closeDialog()
                                }) {
                                    Icon(
                                        imageVector = Icons.Filled.Close,
                                        contentDescription = null
                                    )
                                }
                            },
                            actions = {
                                Text(
                                    "Save",
                                    fontWeight = FontWeight.SemiBold
                                )
                            },
                        )
                    },
                ){
                    Text("Hello world!") // <-- Does not show up
                }
            }
        )
    }
}

Produces:个