private static ThemeBindingProxy GetProxy(string key, string convert, string rtype)
        {
            var dictKey = $"('{key}';'{convert}';'{rtype}')";

            if (_proxies.TryGetValue(dictKey, out var proxy))
            {
                return(proxy);
            }

            proxy             = new ThemeBindingProxy(key, convert, rtype);
            _proxies[dictKey] = proxy;
            return(proxy);
        }
        private static ThemeBindingProxy GetProxy(string key, string convert)
        {
            var dictKey = key + "@@@" + convert + ";";

            if (_proxies.TryGetValue(dictKey, out var proxy))
            {
                return(proxy);
            }

            proxy             = new ThemeBindingProxy(key, convert);
            _proxies[dictKey] = proxy;
            return(proxy);
        }