private void Window_Activated(object sender, EventArgs e)
        {
            if (_ItemToSelect != null)
            {
                CbxInput.SelectedItem = _ItemToSelect;
            }
            else if (CbxInput.Items.Count > 0)
            {
                CbxInput.SelectedIndex = 0;
            }

            CbxInput.Focus();
        }
 private void RadioExisting_Click(object sender, RoutedEventArgs e)
 {
     SetEnableState();
     CbxInput.Focus();
 }