public partial class frm_main : Form
    {
        public frm_main()
        {
            InitializeComponent();
        }
 
        public FileSystemWatcher monitor;
        public ImageSet myImgSet;
 
        /// <summary>
        /// called when a folder is selected
        /// </summary>
        /// <param name="files">A string array of directories</param>
        private void DirSelected(string[] dir)
        {
            try
            {
                DirectoryInfo dirInfo = new DirectoryInfo(dir[0]);
 
                // start monitoring folder
                // DirSelected normally does a bunch of other stuff, currently commented out in my code
                FileWatcher(dirInfo);
            }
            catch (ArgumentException ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
 
        /// <summary>
        /// Sets up the file monitoring
        /// </summary>
        /// <param name="dir">The directory to be monitored</param>
        private void FileWatcher(DirectoryInfo dir)
        {
            // set up file watcher
            if (monitor == null)
            {
                monitor = new FileSystemWatcher();
            }
 
            monitor.Path = dir.FullName;
            monitor.NotifyFilter = NotifyFilters.LastWrite;
 
            //Only monitor .bmp files
            monitor.Filter = "*.bmp";
 
            monitor.Changed += new FileSystemEventHandler(MonitorChanged);
 
            // begin watching
            monitor.EnableRaisingEvents = true;
        }
 
        /// Event Handler for FileSystemWatcher
        private void MonitorChanged(object s, FileSystemEventArgs e)
        {
            MessageBox.Show(e.Name);
        }
    }