WindowsFormsApp1, C#

Language: Layout:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        int leftItem = 0;
        public Form1()
        {
            InitializeComponent();
        }

private void btnPopulate_Click(object sender, EventArgs e)
        {
            leftItem++;
            LstLeft.Items.Add(leftItem.ToString());
        }

private void btnRight_Click(object sender, EventArgs e)
        {
            LstRight.Items.Add(LstLeft.SelectedItem.ToString());
        }

private void btnRightAll_Click(object sender, EventArgs e)
        {
            for (int i = 0; i < LstLeft.Items.Count; i++)
            {
                LstRight.Items.Add(LstLeft.Items[i]);
            }
        }

private void btnClear_Click(object sender, EventArgs e)
        {
            LstLeft.Items.Clear();
            LstRight.Items.Clear();
        }
    }
}

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