This class provides methods for notifying the container's sink regarding control property changes.
CFirePropNotifyEvent has two methods that notify the container's sink that a control property has changed or is about to change.
If the class implementing your control is derived from IPropertyNotifySink, the CFirePropNotifyEvent methods are invoked when you call FireOnRequestEdit or FireOnChanged. If your control class is not derived from IPropertyNotifySink, calls to these functions return S_OK.
For more information about creating controls, see the ATL Tutorial.