void OpenTileSetEditor(string fileName)
 {
     TileSetEditor ed = new TileSetEditor();
     ed.OpenEditor(fileName);
     AttachNewEditor(ed);
 }
        public void OnAddTileSetClicked(object sender, RoutedEventArgs e)
        {
            OpenFileDialog dlg = new OpenFileDialog();
            dlg.InitialDirectory = MainWindow.ContentDir;
            dlg.FileOk += MainWindow.ValidateFileName;

            dlg.Filter = "Tile Sets|*.tls";

            Nullable<bool> result = dlg.ShowDialog();

            if (result == true)
            {
                TileSetEditor tset = new TileSetEditor();
                tset.Editable = false;
                tset.OpenEditor(dlg.FileName);
                tset.TileSelected += OnTileSelected;
                baseMap.tileSets.Add(tset.Tiles);

                TabItem tab = new TabItem();
                tab.Header = tset.Title;
                tab.Content = tset;
                TileSets.SelectedIndex = TileSets.Items.Add(tab);
                OnModify();
            }

            dlg = null;
        }