>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.