WPF window keydown

<Window x:Class="WpfApp175.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp175" KeyDown="Window_KeyDown"
        mc:Ignorable="d" WindowState="Maximized"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Image x:Name="img" ClipToBounds="True" />
    </Grid>
</Window>


//cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data.OleDb;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApp175
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window,INotifyPropertyChanged
    {         
        private List<string> imgsList{ get; set; }
        private int imgsCount { get; set; }
        private int imgIndex { get; set; } = 0;
        public int ImgIndex
        {
            get
            {
                if(imgIndex >= imgsCount)
                {
                    imgIndex = 0;
                }
                this.Title = imgsList[imgIndex];
                return imgIndex;
            }
            set
            {
                imgIndex = value;
                OnPropertyChanged(nameof(ImgIndex));                 
            }
        }
        public MainWindow()
        {
            InitializeComponent(); 
            this.DataContext = this;
            this.Loaded += MainWindow_Loaded;
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propName)
        {
            var handler= PropertyChanged;
            if(handler!=null)
            {
                handler?.Invoke(this,new PropertyChangedEventArgs(propName));
            }
        }

        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            imgsList = new List<string>(System.IO.Directory.GetFiles(@"..\..\Images").ToList());
            img.Source = new BitmapImage(new Uri(imgsList[ImgIndex], UriKind.RelativeOrAbsolute));
            imgsCount = imgsList.Count; 
        } 
        
        private void Window_KeyDown(object sender, KeyEventArgs e)
        {
            if(e.Key==Key.Down)
            {
                if (++ImgIndex >= imgsCount)
                {
                    ImgIndex = 0;
                }
                string imgUrl = imgsList[ImgIndex];
                img.Source = new BitmapImage(new Uri(imgUrl, UriKind.RelativeOrAbsolute));  
            } 
        }
    }
}