When overridden in a derived class, is invoked whenever application code or internal processes (such as a rebuilding layout pass) call ApplyTemplate. In simplest terms, this means the method is called just before a UI element displays in an application. For more information, see Remarks.

public override void OnApplyTemplate()

Public Overrides Sub OnApplyTemplate

public:
virtual void OnApplyTemplate() override

abstract OnApplyTemplate : unit -> unit 
override OnApplyTemplate : unit -> unit