void CreateWatcher (string file)
{
var watcher = new FileSystemWatcher ();
watcher.NotifyFilter |= NotifyFilters.Size;
watcher.Path = Path.GetFullPath (Path.GetDirectoryName (file));
watcher.Filter = Path.GetFileName (file);
watcher.Changed += new FileSystemEventHandler (OnFileChanged);
watcher.EnableRaisingEvents = true;
if (watchers == null)
watchers = new List <FileSystemWatcher> ();
watchers.Add (watcher);
}