Microsoft Outlook provides two events to notify your program that a field (property) in an item has changed. The PropertyChange event is fired whenever a standard Outlook field in an item has changed. Outlook fires the CustomPropertyChange event whenever a user-defined field changes.
A control that is bound to a field does not fire the Click event, whether the control was selected from the Control Toolbox and subsequently bound to a field, or was selected from the Field Chooser. Consequently, you must use the PropertyChange or CustomPropertyChange event to detect user interaction with a bound control.