protected override void Execute(string filename, AbstractProjectBrowserTreeNode node, Action callback)
 {
     try {
         TFS.AddFile(filename);
     }
     catch (Exception ex)
     {
         TFSMessageView.Log("TFSError: Add: " + ex.Message + " (" + filename + ")");
     }
 }
 void AddFile(string fileName)
 {
     TFS.AddFile(fileName);
 }