Flex: Why can't I handle certain events? - apache-flex

Question

In certain cases, I can't seem to get components to receive events.
[edit]
To clarify, the example code is just for demonstration sake, what I was really asking was if there was a central location that a listener could be added, to which one can reliably dispatch events to and from arbitrary objects.
I ended up using parentApplication to dispatch and receive the event I needed to handle.
[/edit]
If two components have differing parents, or as in the example below, one is a popup, it would seem the event never reaches the listener (See the method "popUp" for the dispatch that doesn't work):
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="absolute"
initialize="init()">
<mx:Script>
<![CDATA[
import mx.controls.Menu;
import mx.managers.PopUpManager;
// Add listeners
public function init():void
{
this.addEventListener("child", handleChild);
this.addEventListener("stepchild", handleStepchild);
}
// Handle the no pop button event
public function noPop(event:Event):void
{
dispatchEvent(new Event("child"));
}
// Handle the pop up
public function popUp(event:Event):void
{
var menu:Menu = new Menu();
var btnMenu:Button = new Button();
btnMenu.label = "stepchild";
menu.addChild(btnMenu);
PopUpManager.addPopUp(menu, this);
// neither of these work...
this.callLater(btnMenu.dispatchEvent, [new Event("stepchild", true)]);
btnMenu.dispatchEvent(new Event("stepchild", true));
}
// Event handlers
public function handleChild(event:Event):void
{
trace("I handled child");
}
public function handleStepchild(event:Event):void {
trace("I handled stepchild");
}
]]>
</mx:Script>
<mx:VBox>
<mx:Button label="NoPop" id="btnNoPop" click="noPop(event)"/>
<mx:Button label="PopUp" id="btnPop" click="popUp(event)"/>
</mx:VBox>
</mx:Application>
I can think of work-arounds, but it seems like there ought to be some central event bus...
Am I missing something?

Answer 1

Above is correct.
You are dispatching the event from btnMenu, but you are not listening for events on btnMenu - you are listening for events on the Application.
Either dispatch from Application:
dispatchEvent(new Event("stepchild", true));
or listen on the btnMenu
btnMenu.addEventListener("stepchild",handleStepChild);
btnMenu.dispatchEvent(new Event("stepchild",true));

Answer 2

You are attaching the listener to this when the event is getting dispatched from btnMenu.
This should work:
dispatchEvent(new Event("stepchild", true));
ps. There is really no reason to put an unnecessary 'this' everywhere, unless it's explicitly required to overcome scope issues. In this case you can just leave every this out.