ContactListWithAlphabetScroller.kt

@Composable
fun ContactListWithScroller(
    contacts: List<Contact>,
) {
    val mapOfFirstLetterIndex = remember(contacts) { contacts.getFirstUniqueSeenCharIndex() }
    Row(
        modifier = Modifier.fillMaxSize(),
        verticalAlignment = Alignment.CenterVertically,
    ) {
        ContactList(
            modifier = Modifier.fillMaxHeight().weight(1F),
            contacts = contacts,
            mapOfFirstLetterIndex = mapOfFirstLetterIndex
        )

        AlphabetScroller()
    }
}

Without the fillMaxHeight() when we have small number of contacts it would look like this: