UIElement.AddHandler Method (RoutedEvent, Delegate)
Adds a routed event handler for a specified routed event, adding the handler to the handler collection on the current element.
Assembly: PresentationCore (in PresentationCore.dll)
An identifier for the routed event to be handled.
A reference to the handler implementation.
You can add the same handler for the same event multiple times without raising an exception. However, the handler is actually invoked multiple times when the event is handled. Therefore, consider how this behavior might have side effects that should be accounted for in your handler implementation.
You typically use this method to provide the implementation of the "add" accessor for the Microsoft .NET event access pattern of a custom routed event.
Available since 3.0