Mechanics of reference counters in GC?

Question

Hi all,
I was thinking about Flash GC the other day and came up with a question about how reference counting would work in the following 4 class scenario (assume GuiMain is the movie's document class):
    package com.gui {    
import flash.display.MovieClip;        
public class GuiMain extends MovieClip {        
private var button1Handle:Button1;        
public function GuiMain() {            
// constructor code            
button1Handle = new Button1();            
addChild(button1Handle);           
killButton1();        
public function killButton1(){            
removeChild(button1Handle);            
button1Handle = null;        
package com.gui {    
import fl.controls.Button;   
import flash.display.*;        
public class Button1 extends Sprite {        
private var button2Handle:Button2;        
private var tester:Test;        
public function Button1() {            
// constructor code           
button2Handle = new Button2();            
tester = new Test();        
package com.gui {        
public class Button2 {        
public function Button2() {            
// constructor code        
package com.gui {    
import flash.display.MovieClip;    
import flash.events.Event;            
public class Test extends MovieClip{        
public function Test() {            
// constructor code           
addEventListener(Event.ENTER_FRAME, yellLoudly);        
public function yellLoudly(e:Event){                        
trace("AAAH!!!");        
When the Button2 and Test instances are created in Button1, I would expect their reference counters to increment. The question is, do their reference counters decrement accordingly when the Button1 object that created them is removed from the display list and nulled out? I tested this code and the event listener in the Test class does seem to shut off, but that doesn't necessarily mean that it or the Button2 instance are eligible for GC. Even if they were, it might only be under Mark and Sweep, which is slower than reference count-based GC.
One obvious solution would be to have the Button1 class remove listeners from/null out references it makes when it is time for it to be removed like so:
package com.gui {    
import fl.controls.Button;    
import flash.display.*;        
public class Button1 extends Sprite {        
private var button2Handle:Button2;        
private var tester:Test;        
public function Button1() {            
// constructor code            
button2Handle = new Button2();            
tester = new Test();        
public function destroyRefs(){                  
button2Handle = null;                  
tester.removeEventListener(Event.ENTER_FRAME, tester.yellLoudly);                  
tester = null;           
but in a real program, where I may be working with multiple references to the same object from different classes (via passing in the original references in constructors) wouldn't setting the reference in one class to null cause the value of all other references to the same object to also become null? That would certainly be undesirable...
The main question is as follows: when the only reference to Button1 is nulled out, do all the the objects it references have their reference counters decremented (either immediately or when the Button1 object is garbage collected)?
Also, is there a way to view all instances of an object that exist in real time and/or their reference count values through the Flash debugger?  A detailed profiler like that would really help in figuring these questions out...
thanks,
CCJ

Answer 1

to answer the last bit, flash builder premium has a good profiler and you could also try Monster Debugger - its free and i think it has a profiler