private void HistoryBtn_Click(object sender, RoutedEventArgs e)
        {
            var history = new HistoryNyse();

            history.Show();
            this.Close();
        }
        //keyboard button handler :::
        private void HandleKey(object sender, KeyEventArgs e)
        {
            if (e.Key == Key.H)
            {
                var history = new HistoryNyse();
                history.Show();
                this.Close();
            }

            if (e.Key == Key.I)
            {
                //Prevent multiple import windows to be opened
                foreach (Window w in Application.Current.Windows)
                {
                    if (w is Import)
                    {
                        isWindowOpen = true;
                        w.Activate();
                    }
                }

                //If import window is not open
                if (!isWindowOpen)
                {
                    Import newwindow = new Import();
                    newwindow.Show();
                }
            }
        }