>>Hi Fabio,
>>
>>>

>>>* textbox.ProgrammaticChange
>>>
>>>IF m.this.Value == EVAL(m.this.ControlSource)
>>>    NODEF
>>>ENDIF
>>>

>>
>>If the control source can hold NULL values, you also need to check for all three combinations of NULL. Otherwise you would never detect a change when any of the values is NULL.
>
>Hi Christof,
>
>of course!
>
>On the forum I prefer show the evidence,
>the exact solution is not usefull for a developer.
>
>By the way,
>it is a annoyance that in VFP , MS SQL and others,
>there is not a comparison including the null value.
>Every solution require a double evaluation.

In our case I don't think we can have NULL in this field, but thanks a lot for mentioning this.