Silverlight ToolTip Overview
RadToolTip is a set of controls that allows you to specify and show tooltips. It consists of:
RadToolTip - the content control that creates a pop-up window that displays information for an element in the interface.
RadToolTipService - the service that provides properties and events to control the display and behavior of tooltips.
RadToolTipContentView - a control that enables theming for RadToolTip (read more).