>David,
>
>A control will update its controlsource just before the Valid event fires. The Interactivechange is too early in the event sequence.
.... (snip)

Thank you Jim. That makes it quite clear. Is there a good comprehensive reference on the event firing and action sequence for the range of visible controls/forms in VFP?

In my case, a spinner control doesn't update the control source until the focus leaves the control. And you can't use the debugger to test these things because firing the debug window causes the control to update its source!.