Occurs when the mouse (or a stylus) enters the bounding area of a UIElement.
Assembly: System.Windows (in System.Windows.dll)
The event is raised in response to the mouse (or a stylus) moving into the object's bounding area. The event precedes the MouseMove event for the object. The event is not raised if the mouse (or a stylus) did not actually move. For instance, is not raised if the mouse pointer (or the stylus tip) remains stationary, and an object with a handler has its position animated or otherwise adjusted to move under the mouse pointer.
You can define multiple events for objects in XAML content. However, if a child object and its parent object both define a event, the parent object's event occurs before the child object's event. This is not a case of a bubbling event; it indicates only that the mouse (or stylus) has entered both objects, potentially at different times depending on the layout and the composition of the visual tree.
The mouse position that is reported in the event data may not be exactly on the boundary of the object because of the coalescing of mouse movements.
events do not route, they can only be handled on the element that raises them. For details, see the "MouseEnter and MouseLeave Events" section of Mouse Support.
MouseEnter and OnMouseEnter
Controls that inherit can provide handling for the event that acts as handler for all instances, by overriding the OnMouseEnter method. OnMouseEnter can be useful either for setting visual state, or for public or internal state properties. For instance, Slider implements OnMouseEnter in order to check the Thumb element's value for IsDragging (which invokes a particular behavior mode), and also to set visual state. For more information, see OnMouseEnter.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.