The event handler receives an argument of type DevExpress.Xpf.Diagram.DiagramQueryItemSnappingEventArgs containing data related to this event.
The SnapTo event's parameter returns the item suitable for snapping (nearest in height/width when the end-user resizes an item or one lying on the same line when the end-user drags an item). The item that is being moved or resized is returned by the Item parameter. The Allow parameter specifies whether to enable snapping to the suitable item.