jetpack compose - TopAppBar actions

MainActivity.kt

package com.cfsuman.jetpackcompose

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.*
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.material.Text
import androidx.compose.material.TopAppBar
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier


class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            GetScaffold()
        }
    }


    @Composable
    fun GetScaffold(){
        val counter:MutableState<Int> = remember{ mutableStateOf(0)}

        Scaffold(
            topBar = { TopAppBarContent(counter) },
            content = {MainContent(counter)},
            backgroundColor = Color(0xFFEDEAE0)
        )
    }


    @Composable
    fun TopAppBarContent(counter: MutableState<Int>) {
        TopAppBar(
            title = { Text(text = "Compose - TopAppBar Actions")},
            backgroundColor = Color(0xFFC0E8D5),
            actions = {
                IconButton(onClick = {
                    counter.value++;
                }) {
                    Icon(
                        Icons.Filled.AddCircle,
                        contentDescription = "Localized description"
                    )
                }

                IconButton(onClick = {
                    counter.value--;
                }) {
                    Icon(
                        Icons.Filled.Close,
                        contentDescription = "Localized description"
                    )
                }
            }
        )
    }


    @Composable
    fun MainContent(counter: MutableState<Int>){
        Box(
            modifier = Modifier.fillMaxSize(),
            contentAlignment = Alignment.Center
        ){
            Text(
                text = "${counter.value}",
                style = MaterialTheme.typography.h1
            )
        }
    }


    @Preview
    @Composable
    fun ComposablePreview(){
        //GetScaffold()
    }
}