In JScript, you can handle the events defined by another class, but you cannot define your own.
Managed Extensions for C++
public: __event MouseLeave
The event handler receives an argument of type containing data related to this event. The following MouseEventArgs properties provide information specific to this event.
OriginalSource (Inherited from )
Target Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, Windows Vista, Windows Server 2008 family