Mouse.MouseEnter Attached Event
Occurs when the mouse pointer enters the boundaries of an element.
Assembly: PresentationCore (in PresentationCore.dll)
This is an attached event. WPF implements attached events as routed events. Attached events are fundamentally a XAML language concept for referencing events that can be handled on objects that do not define that event, which WPF expands upon by also enabling the event to traverse a route. Attached events do not have a direct handling syntax in code; to attach handlers for a routed event in code, you use a designated Add*Handler method. For details, see Attached Events Overview.
This event uses the direct event handling routing strategy. Direct routed events are not raised along a route (they are only handled in the same element on which they are raised). They do, however, enable other aspects of routed event behaviors, such as event triggers in styles.
Although this event is used to track when the mouse enters an element, it is also reporting the IsMouseOver property has changed from false to true on this element.