/// <summary>
/// Method called when the 'OK' button is clicked.
/// </summary>
/// <param name="sender">Sender.</param>
/// <param name="e">Event args.</param>
private void OkClicked(object sender, EventArgs e)
{
// Save the DRM username and password in the preferences.
AppPreferences.SetDRMUsername(usernameEntry.Text);
AppPreferences.SetDRMPassword(passwordEntry.Text);
AppPreferences.SetDRMServer(serverPicker.SelectedIndex == 0 ? SERVER_PRODUCTION : SERVER_TEST);
ClosePopup();
}