When overridden in a derived class, returns an alternative user interface (UI) parent for this element if no visual parent exists.
Assembly: PresentationCore (in PresentationCore.dll)
The default virtual implementation of this method returns null. FrameworkElement provides a practical implementation.
Alternative parents are used for event routing, in cases where an element creates an alternative parent structure so that its events are routed in a way that diverges from the standard pattern of routing up the visual tree to the standard parent, or downward in the preview routing strategy.