// used for adding a subscription
        public NewSubscriptionWindow(MainWindowViewModel mainWindowViewModel)
        {
            _vm = new NewSubscriptionWindowViewModel(mainWindowViewModel);
            DataContext = _vm;

            InitializeComponent();
        }
        // used for editing a subscription
        public NewSubscriptionWindow(LogSubscription logSubscription)
        {
            _vm = new NewSubscriptionWindowViewModel();
            DataContext = _vm;

            InitializeComponent();

            txtName.Text = logSubscription.Name;
            ddlPlugin.SelectedValue = logSubscription.PluginTypeName;
            LogProviderPluginDropDownSelectionChanged(this, null);
            ((ISubscriptionSettings) grpSettings.Content).SettingsXml = logSubscription.Url;

            btnAdd.Visibility = Visibility.Hidden;
            btnUpdate.Visibility = Visibility.Visible;

            _logSubscription = logSubscription;
        }