Question

I would like to show the popup window warning that internet connection is not available, but I do not know how to pop a simple pop up window on the screen (something like text block) and then close the app after OK.

 void wc_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e) {
        SyndicationFeed feed;
        try {
            using (XmlReader reader = XmlReader.Create(e.Result)) {
                feed = SyndicationFeed.Load(reader);
                lista.ItemsSource = feed.Items;
            }
        } catch (WebException we) { POP IT HERE then close the app;}
    }

Answer 1

use

MessageBox.Show("you text");