How i can create and dispatch the custom events in the modules.
As long as you have the custom event classes accessible with import myClassDir.myClassSubdir.*;
you should be able to create custom events with var myEvt:MyCustomClass - new MyCustomClass(); and then dispatchEvent(myEvt);
You can communicate with the main app using mx.core.Application.applilcation or using parentDocument or parentApplication, though custom events are the way to go.
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Add the Event class to the main app. The main app attaches a listener to the module class instance. The module dispatches the event.
Flex SDK Developer
Adobe Systems Inc.