The official blog of the Windows Presentation Foundation Team
There are six properties on each Ribbon control that enable creation of rich ToolTips such as the one shown below.
The use of any of these six properties causes a RibbonToolTip instance to be created and used as the ToolTip for the Ribbon control. It is always possible to override this behavior by explicitly creating a ToolTip. However note that a RibbonToolTip in addition to providing a rich template also provides the service of correctly positioning iself below the Ribbon instead of the default position next to the mouse cursor. So it is highly recommended to use a RibbonToolTip instance, even if you wanted to create a custom one.
Read next post to learn about adding RibbonGallery to your Ribbon app.