Assembly: PresentationFramework (in PresentationFramework.dll)
The ToolTipOpening event occurs immediately before a tooltip opens. This event does not occur if the tooltip is not defined or if the tooltip content is set to null.
This field registers the behavior of the ToolTipOpening event for classes that use this service. The FrameworkElement and FrameworkContentElement classes both implement the ToolTipService and expose this event through the common language runtime (CLR) accessors FrameworkElement.ToolTipOpening and FrameworkContentElement.ToolTipOpening.
Available since 3.0