R – visual change event

Have you tried signing up for 'Event.OPEN' to see if the connection is opening correctly? If you're doing this per chunk - perhaps that event or lack thereof would help?

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Can you also try setting useCache to false on your URLRequest?

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I assume you're urlLoader is globally referenced... If not, while you're waiting for async behavior, something evil like GC might hurt you ... But - skipping that, if you call 'bytesTotal' while you're waiting for something to happen - does it always return zero?

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Also - check the URL in the cases where NOTHING happens - because online I've found some mention that if the server is unreachable there are no events fired (though there is some argument around that)...

The way you have your pseudocode setup right now, you'd have to subclass all the different containers and add a handles_key property to each one. You may want to externalize the functionality to a separate class like this:

<KeyHandler target="{tab1}" handlesKeys="pgup,left,right"/>

As for actually catching the events, you'll need to add a KeyboardEvent.KEY_DOWN listener on the UIComponent you're wanting to listen to. You'll need to set the useCapture argument of addEventListener() to true as well. This will let you capture the event and prevent it instead of the event hitting the object and bubbling up.

target.addEventListener(KeyboardEvent.KEY_DOWN, target_onKeyDown, true);

Inside your target_onKeyDown event, check to see if you have a match for one of your keys you want to handle and if there is a match, call event.stopImmediatePropagation() or event.preventDefault() depending on what you need to do.

The Flex 3 Language Reference gives a good explanation of event propagation and keyboard events:

http://livedocs.adobe.com/flex/3/langref/flash/events/Event.html