Occurs when the clock's CurrentState property is updated.
Assembly: PresentationCore (in PresentationCore.dll)
Use the CurrentStateInvalidated event when you want to be notified if when the clock starts, stops, or fills. The Object parameter of the EventHandler event handler is the Clock whose state was invalidated.
Although this event occurs when the ClockState becomes invalid, that doesn't necessarily mean the ClockState changed: a Clock that switches from Active to Filling and then back to Active in the same tick will cause this event to fire, but its CurrentState property won't actually change.