Invoked whenever the ToolTipOpening routed event reaches this class in its route. Implement this method to add class handling for this event.
Assembly: PresentationFramework (in PresentationFramework.dll)
This method has no default implementation. You should still call base() in case an intermediate class in the inheritance has implemented this method.
The purpose of this method is somewhat similar to common language runtime (CLR) event pattern On* methods: it provides the means to handle the matching event from derived classes with a class handler instead of an instance handler. In this case the matching event is a routed event. The implementation pattern of the On* methods is different for routed events because the routed event may have been raised by a child element, not necessarily the element that will invoke handlers, so your implementation will need to take the event arguments' source properties into account (and should not try to re-raise the event in most cases). Subclasses of FrameworkContentElement could choose to call private class handler methods when the event is received along the route. One potential scenario is to take the arguments of the event and deliberately mark the event as handled to shorten the route.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)