>>>>Why don't you make a class derived from textbox, add a property, in When method save old value to the property, in Valid... etc.?
>>>
>>>Good idea. This is probably what I'll do. Thanks.
>>
>>Well, now I'm sure that this is not what you're looking for. :-)
>
>In the first approach, I'll probably add a property on each of my class control to handle the value from the When() to the Valid(). Yes, this is what I was looking for. :)

You an also use GETFLDSTATE() if it's about a database field. But I don't know if it works in Valid and I think it's not so good (because you'll can use it only for fields).