public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
{
TypeTypeConverter converter = new TypeTypeConverter();
value = converter.ConvertFrom(context, CultureInfo.CurrentCulture, value);
value = base.EditValue(context, provider, value);
value = converter.ConvertTo (context, CultureInfo.CurrentCulture, value, typeof(string));
return value;
}