controlmymonitormanagement/DellMonitorControl/App.xaml.cs

using Hardcodet.Wpf.TaskbarNotification;
using System.Windows;

namespace DellMonitorControl
{
    public partial class App : Application
    {
        private TaskbarIcon? _trayIcon;
        private MainWindow? _mainWindow;

        private void Application_Startup(object sender, StartupEventArgs e)
        {
            _trayIcon = (TaskbarIcon)FindResource("TrayIcon");
            _trayIcon.TrayLeftMouseUp += TrayIcon_Click;

            _mainWindow = new MainWindow();
            _mainWindow.Show();
        }

        private void TrayIcon_Click(object sender, RoutedEventArgs e)
        {
            if (_mainWindow == null) return;

            if (_mainWindow.IsVisible)
                _mainWindow.Hide();
            else
            {
                _mainWindow.Show();
                _mainWindow.Activate();
            }
        }

        protected override void OnExit(ExitEventArgs e)
        {
            _trayIcon?.Dispose();
            base.OnExit(e);
        }
    }
}