MainWindow.xaml.cs

using System;
using System.Collections.Generic;
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 WpfApp_Learning
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void ButtonAddName(object sender, RoutedEventArgs e)
        {
            if (!string.IsNullOrWhiteSpace(txtName.Text) && !lstNames.Items.Contains(txtName.Text))
            {
                lstNames.Items.Add(txtName.Text);
                txtName.Clear();
            }
        }


        private void pnlMainGrid_MouseUp(object sender, MouseButtonEventArgs e)
        {
            MessageBox.Show("You clicked me at " + e.GetPosition(this).ToString());
        }

        private void StackPanel_MouseUp(object sender, MouseButtonEventArgs e)
        {

        }
    }
}