ComposeNestedScrollSampleWithConnection.kt

val appBarOffset by remember { mutableIntStateOf(0) }

Surface(
   modifier = Modifier.fillMaxSize(),
   color = MaterialTheme.colorScheme.background
) {
   val connection = remember {
       object : NestedScrollConnection {
           override fun onPreScroll(
               available: Offset,
               source: NestedScrollSource
           ): Offset {
               return super.onPreScroll(available, source)
           }
       }
   }

   Box(Modifier.nestedScroll(connection)) {
       LazyColumn(contentPadding = PaddingValues(top = AppBarHeight)) {
           items(Contents) {
               ListItem(item = it)
           }
       }
       
       TopAppBar(
           modifier = Modifier.offset { IntOffset(0, appBarOffset) },
           title = { Text(text = "Jetpack Compose") },
           colors = TopAppBarDefaults.topAppBarColors(
               containerColor = Purple40,
               titleContentColor = Color.White
           )
       )
   }
}