>Ok, so this makes my scenario consistent: for CommandButton, Checkbox,... Click always triggers Valid, which is always followed by a second When.
>What do you think, is this a bug, or is it a bad design choice caused by trying to fit Valid in the event list of CommandButton, Checkbox,... ?

A bad design.
Honestly, the whole design of the visual events of VFP is very inaccurate

>Do we need Valid for a CommandButton in VFP? BTW, I still don't understand what do you mean when you say that return .F. in Valid is ignored?
>

On a textbox RETURN .F. in Valid, stop the lostfocus process ( true 95% )
and RETURN someobject set the focus into someobject.
On a checkbox RETURN someobject work, but RETURN .F. doesn't.