ToolTipService.PlacementRectangle Attached Property
Gets or sets the rectangular area relative to which the tooltip is positioned.
Assembly: PresentationFramework (in PresentationFramework.dll)
The PlacementRectangle property specifies a Rect structure relative to which the ToolTip control is positioned when it opens. If PlacementTarget is not null, the Rect structure is defined relative to the PlacementTarget object. Otherwise, the specified Rect structure is defined relative to the upper-left corner of the screen.