public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return ((TimeSpan)value).TotalSeconds.ToString(CultureInfo.InvariantCulture);
    }

    /// <see cref="IValueConverter.ConvertBack"/>
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return TimeSpan.FromSeconds(int.Parse((string) value, NumberStyles.None, CultureInfo.InvariantCulture));
    }