HtmlRenderer.HtmlToolTip
System.Windows.Forms.ToolTip
Inherits directly from System.Windows.Forms.ToolTip, the only difference is that the ToolTip text will be interpreted as HTML. All HTML Renderer Rules apply.
Try the Sample Form and place the mouse over the button to change the ToolTip of the button.
All Tool tips are wrapped in a TABLE with the style of this paragraph