Invoked just before the IsKeyboardFocusWithinChanged event is raised by this element. Implement this method to add class handling for this event.
Assembly: PresentationCore (in PresentationCore.dll)
This virtual method is raised when the value of the IsKeyboardFocusWithin dependency property changes its value. The virtual method is raised first and can manipulate the event data as necessary. Then the IsKeyboardFocusWithinChanged event is raised with that same event data instance. Notice that the IsKeyboardFocusWithinChanged event is not a routed event. Therefore, you cannot mark it as handled in the class handler.
This method has no default implementation. Because an intermediate class in the inheritance might implement this method, we recommend that you call the base implementation in your implementation. You may call base either before or after your special handling, depending on your requirements.