private void bFindDataGrids_Click(object sender, RoutedEventArgs e)
        {
            string activetab = GetActiveTabOfActiveDataset(); //get active tab

            switch (activetab)
            {
            case "datagrid":
                if (fdw == null)
                {
                    fdw       = new FindDatagridWindow(this);
                    fdw.Owner = this;
                    fdw.WindowStartupLocation = System.Windows.WindowStartupLocation.CenterOwner;
                }
                fdw.Show();
                break;

            case "vargrid":
                if (fvw == null)
                {
                    fvw       = new FindVargridWindow(this);
                    fvw.Owner = this;
                    fvw.WindowStartupLocation = System.Windows.WindowStartupLocation.CenterOwner;
                }
                fvw.Show();
                break;

            default:
                break;
            }
        }
 public void CloseFindVargrid()
 {
     fvw = null;
 }