Finally got anwser (after digging up some documentation - a lot of that). First of all, there is an attribute Type Converter
that a pleasant walk, how to implement it, here . This is what led me to this.
:
GetStandardValuesSupported(ITypeDescriptorContext context), true GetStandardValues(ITypeDescriptorContext context), StandardValuesCollection .
, :
[TypeConverter(typeof(MyClassConverter))]
public MyClass MyProperty { get; set; }
.