10.07.2015 Views

Programming Guide - Actian

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Event-based <strong>Programming</strong>If there is a chain of events, OpenROAD queues all the child events for the firstevent in the chain before moving on to the second event in the chain. Forexample, field A and field B belong to subform Y. If the user changes the datain field A and tabs out of field A to field B, the events are triggered in the ordershown in the following illustration:Menu EventsMenu events are events triggered when a user selects a menu item. Menuevents are simpler than field events because they have fewer available events.These menu events are:Click eventThe three menu fields (menu button, menu toggle, and menu list) all havea Click event, which is triggered when the user selects the menu item.SetValue eventThe menu toggle and menu list fields also have a SetValue event, which istriggered when the user changes the value of the menu item—that is,switches the toggle setting or selects a new item from the list.Validate eventThe menu toggle and menu list fields also have a Validate event, which istriggered at exactly the same places as the SetValue event, but isprocessed before the SetValue chain. Therefore, if a Validate event blockcontains a resume statement, control returns to the frame withouttriggering the SetValue event.326 <strong>Programming</strong> <strong>Guide</strong>

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