public void DownloadHoldingsAsync(string portfolioID, int viewIndex, object userArgs)
 {
     if (this.IsLoggedIn)
     {
         HoldingsDownload dl = new HoldingsDownload();
         dl.Settings.Account = this;
         dl.Settings.PortfolioID = portfolioID;
         dl.AsyncDownloadCompleted += this.HoldingsDownload_Completed;
         dl.DownloadAsync(userArgs);
     }
     else { throw new NotSupportedException("The user is not logged in."); }
 }