title: How do I create/handle IsMouseOverChanged
body: <p>I like the functionality of IsMouseDirectlyOverChanged, but it only works for the topmost elements.  What I really want to do is monitor the IsMouseOver property of a control, regardless of its z-index, and receive notification when IsMouseOver is modified.  If I owned this property, I could do INotifyPropertyChanged, but unfortunately it's owned by UIElement.  Still learning the ropes of WPF, so maybe this is easy, but I'm not familiar with how to monitor properties that belong to parent classes.  Unlike IsMouseDirectlyOver, IsMouseOver doesn't have a changed event attached.</p>