void loginTextbox_TextChanged(object sender, TextChangedEventArgs e)
        {
            if (!IsInitialized)
            {
                return;
            }
            TextBox textBox = sender as TextBox;

            if (textBox != null)
            {
                API.UrlShortener.ILinkShortener shortener = textBox.DataContext as API.UrlShortener.ILinkShortener;
                if (shortener != null)
                {
                    shortener.Login = textBox.Text;
                }
            }
        }
        void passwordTextbox_PasswordChanged(object sender, RoutedEventArgs e)
        {
            if (!IsInitialized)
            {
                return;
            }
            PasswordBox passwordBox = sender as PasswordBox;

            if (passwordBox != null)
            {
                API.UrlShortener.ILinkShortener shortener = passwordBox.DataContext as API.UrlShortener.ILinkShortener;
                if (shortener != null)
                {
                    shortener.Password = passwordBox.Password;
                }
            }
        }