Flex events, priorities and threads

Question

Hello,
I have been reading from several places that flex is entirely single threaded, that two pieces of code will never be executed concurently, even when using timer events, and so on...
On the other hand, http://livedocs.adobe.com/flex/3/html/help.html?content=events_09.html says:
Even if you give a listener a higher priority than other listeners,
there is no way to guarantee that the listener will finish executing
before the next listener is called. You should ensure that listeners do
not rely on other listeners completing execution before calling the
next listener. It is important to understand that Flash Player does not
necessarily wait until the first event listener finishes processing
before proceeding with the next one.
Could someone explain how a listener can be called "before the previous listener is finished", if the statement regarding single threading is true???
I am running into a very nasty bug that I can't explain unless I have a race condition between two functions accessing the same ressource inside events. It is really looking like event callbacks are executed in separated treads, which would be consitent with Adobe doc about events and priorities.
Thank you in advance for any hint...
Pierre

Answer 1

Sure it helps.  It means that a whole class of possible causes has been
eliminated.
Anyway, describe your problem in more detail.  Keep in mind that while you
don't have to worry about concurrency issues, you do have to worry about
asynchronicity issues.  Network calls, for example, are asynchronous, which
means that they do not block the UI, and their event handlers will run
later, when the response returns (but it won't interrupt other actionscript
processing).  I don't believe that responses are guaranteed to return in the
order requested and that can cause your code to run in a different order
than expected.