>Well, if you use pessimistic locking in your application, there are functions in VFP that allow to check if record is locked by another user. Than you can do this in timer event and refresh status of controls on form accordingly.

Even without a timer, if he employs a button which specifically starts an edit, he can run the checking from the button's click.
Another way would be to have some common code to be called from any control's .InteractiveChange event, which would check for a property... mmm, let's say ThisForm.WeGotItLocked, and another one, ThisForm.SomeoneLockedIt. So if both are .f. (as they should initially be), we'd try to lock. Succeeding or failing, we'd set one of them, and allow or disable further editing accordingly.