Programming Guide - Actian

Event-based ProgrammingEvent ChainsA simple user action often triggers a series of events called an event chain. Anevent chain is a linked series of events triggered by a starting event. Forexample, each time the user changes some data in an entry field and thenmoves to another field, three events are triggered, as shown in the followingillustration:Another important event chain occurs when the user selects a field. Each timethe user selects a field, the following three events are triggered:• UnSelect event for previous field• Select event for current field• SelectionChanged event for the frameEvent chains do not include user events, except when you issue theSendUserEvent method with a focusbehavior parameter setting ofFT_SETVALUE or FT_TAKEFOCUS. In these instances, if the value of thecurrent field has changed, the event chain begins with a SetValue event andincludes the user event.Important! If you provide more than one event block for an individual field,you must consider the order in which the events are triggered.Child EventsWhen a field belongs to a composite field, a single user action on the child fieldtriggers a corresponding event for the parent field. For example, if field Abelongs to subform X, and the user selects field A, a Click event is triggeredfor field A and a ChildClick event is triggered for subform X, its parent field.324 Programming Guide