>>>>Wow, thanks a lot - I didn't know that was possible. I always used the Refresh() event, but that looks clumsy compared to just assigning the ControlSource.
>>>
>>>The side effect is that the control become Read-Only. It is a bug for me.
>>
>>I don't think this is a bug. I mean, what would you expect?
>>
>>You can assign a value to a variable, but not to an arbitrary expression.
>>
>
>
>>For instance, the following is a valid assignment:
>>
>>

>>x = a + 1
>>

>>
>>But the following is not:
>>
>>

>>x + y = a + 1
>>

>>
>>I mean, where should "a + 1" in this example be copied to?
>>
>>As I see it, the case is similar for the ControlSource, which implies a "store" or a "replace", depending on the case.
>
>I don't agree.
>
>The control is not a variable, it is a two way visual data interface
>( user : read with eyes write with the keyboard and the Mouse)
>( ControlSource : read with eval("Controlsource") write with a copy Value into the ControlSource )
>
>I'm a developer and I want a full control of the four operations!
>
>Then, when the Control read the ControlSource it refresh the .Value ( GotFocus,Refresh,valid,...),
>but if I set ReadOnly = .F. the the User is free to update the Value,
>when controlSource= "(exp)" VFP must execute this sequence:
>

>* skip write into ControlSource
>* execute the Valid routine, whre I can use the Value
>* if Valid don't stop the process (return False,0,this,NULL...)  then refresh the Value with eval(exp)
>

>
>This open a lot of data input possibilities.
>
>Example: field = datatime visual the date part only
>

>ControlSource = "TTOD(alias.field)"
>* Valid
>REPLACE IN alias field WITH m.this.Value
>

>
>Now, try to implement date part input into a grid.
>
>I have work one year for destroy the VFP ControlSource logic.
>Now I have a true visual data input/output interface.

I see. This looks similar to _access and _assign properties. I still think of this more as a "missing feature" than as a "bug", but it is obvious that the fact that the control is ReadOnly interferes with your desires.