private DockTreeZOrder FromString(string s)
        {
            Dock first, second, third, fourth;

            string[] strings = s.Split(',');

            if (strings.Length != 4)
            {
                throw GetConvertFromException(s);
            }

            first  = (Dock)s_dockConverter.ConvertFrom(strings[0].Trim());
            second = (Dock)s_dockConverter.ConvertFrom(strings[1].Trim());
            third  = (Dock)s_dockConverter.ConvertFrom(strings[2].Trim());
            fourth = (Dock)s_dockConverter.ConvertFrom(strings[3].Trim());

            if (!DockTreeZOrder.CheckValues(first, second, third, fourth))
            {
                throw GetConvertFromException(s);
            }

            return(new DockTreeZOrder(first, second, third, fourth));
        }