kendall's code

   public object Convert(object value, Type targetType, object parameter, CultureInfo culture, bool convertBack = false)
    {
        if (Converters.Count == 0 && value != null && value.GetType() == targetType)
        {
            return value;
        }
        foreach (IValueConverter converter in Converters)
        {
            object temp = converter.Convert(value, targetType, parameter, culture, convertBack);
            if (temp != null)
            {
                return temp;
            }
        }
        return null;
    }