Question: On occasion, I have wanted to push a closure onto ActionScript's event stack so that it will be executed after the current event handler. Right now I use `setTimeout(closure, 0)`. Is there a more direct way of doing this?

Answer: 
setTimeout(closure, 0) is creating a new event stack. I don't understand your objective if this solution isn't working for you. What is the goal you're trying to accomplish? 

Flex has ENTER\_FRAME events, Timer, callLater, setTimeout, setInterval, all which delay calls and create new execution stacks. 

Are you trying to inject code into the current stack? If so, you might need to look at something like this: <http://en.wikipedia.org/wiki/Active_object>. The idea being that you push functions (closures) into an array, and the active object controller pulls the next one off the list when the previous one has run to completion. That's the simplest case. You can write a more complicated one that will have priority stacks like high, medium, low, with your own schedule management system. (e.g., low get promoted after waiting too long).

But hey! The devil is in the details. What's the goal?
Take a look at capture and bubbling phases of the as3 events. 
I found this nice chapter that explains clearly the proccess: <http://books.google.com/books?id=yFNZGjqJe9IC&lpg=PA250&ots=oPB9HXIby7&dq=flash%20event%20bubbling%20phase&pg=PA250#v=onepage&q=&f=false>

And also check the EventDispatcher class documentation that explain the use of this different phases.