UIElement.HasEffectiveKeyboardFocus Property
Gets a value that indicates whether the UIElement has focus.
Assembly: PresentationCore (in PresentationCore.dll)
Subclasses can override this property to specify when the element has keyboard focus. This is useful when your UIElement contains elements that can have keyboard focus and you want your element to report that it has focus.
.NET Framework
Available since 4.5
Available since 4.5