3D: z-Sorting make blinking my Sprites

Question

It seems that I can get working the z-Sorting on my projects.
I have created 3 bubbles, which are moving following an ellipsis rotation on a 2D plan laid out in 3D on the scene. During the z-Sorting, my bubbles are blinking, as if they were constantly interchanged between them.
Here is the code responsible:
private var bubbles:Vector.<Bubble> = new Vector.<Bubble>();
        public function ReorderChildren()
            bubbles.sort(function compare(x:Bubble, y:Bubble):int { return y.z - x.z; });
            for (var ind:int = 0; ind < bubbles.length; ind++)
                root.addChild(bubbles[ind]);
However, it seems that removing the for loop (which performs root.addChild), and apply the same sorting function upon the vector, bubbles are still blinking.
var bubbles:Vector.<Bubble> = new Vector.<Bubble>();
// Adding bubbles to the scene
for each (var flyer:FlyerVO in flyers) {
    var bubble:Bubble = new Bubble(flyer);
    root.addChildAt(bubble);
    bubbles.push(bubble);
public function ReorderChildren() {
    bubbles.sort(function compare(x:Bubble, y:Bubble):int { return y.z - x.z; });
The simple fact that sorting the vector (which contains only references to Bubble object) make them blink. Is this a bug ?
> Is there any way to attach my project folder to illustrate the bug ?

Answer 1

wow... I guess getting to the question instead of going over, no doubt important, details.
If you would test the snippets in a real environment you'd see the result. Just a reassuring confirmation to the original poster maybe...
Past following code in frame one of .fla and see the effect on the indicated lines (after some code alterations I noticed it disappearing with some sorts and it not appearing at all with just two 'conficting' positions:
import flash.display.Sprite;
import flash.events.Event;
var bubbles:Vector.<Sprite> = new Vector.<Sprite>();
var s:Sprite;
s = createCircle( 0xFF0000 );
s.x = 200;
s.y = 200;
s.z = 10;
bubbles.push( s );
s = createCircle( 0x00FF00 );
s.x = 220;
s.y = 220;
s.z = 20;
bubbles.push( s );
s = createCircle( 0x0000FF );
s.x = 200;
s.y = 240;
s.z = 20;
bubbles.push( s );
// remove next circle creation to not see effect
s = createCircle( 0xFF00FF );
s.x = 180;
s.y = 220;
s.z = 20;
bubbles.push( s );
addEventListener( Event.ENTER_FRAME, ReorderChildren );
function createCircle( c:int ):Sprite
     var s:Sprite = new Sprite();
     s.graphics.beginFill( c );
     s.graphics.drawCircle( 0, 0, 20 );
     s.graphics.endFill();
     return s;
function ReorderChildren( event:Event )
     //bubbles.sort( highFirst ); // OK
     //bubbles.sort( lowFirst ); // jitter
     bubbles.sort( compare ); // jitter
     for (var ind:int = 0; ind < bubbles.length; ind++)
          addChild(bubbles[ind]);
function compare(a:Sprite, b:Sprite):int
     return b.z - a.z;
// higest value first in array
function highFirst(a:Sprite, b:Sprite):int
     if( a.z > b.z )
             return 1;
     else if ( a.z < b.z )
             return -1;
     else
          return 0;
// higest value first in array
function lowFirst(a:Sprite, b:Sprite):int
     if( a.z < b.z )
             return 1;
     else if ( a.z > b.z )
             return -1;
     else
          return 0;
However, testing some nicer, AFAIK also technically correct, code I get no nasty sorting problems:
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.Point;
var bubbles:Vector.<Sprite> = new Vector.<Sprite>();
var s:Sprite;
var p:Point;
var center:Point = new Point( 200, 200 );
s = createCircle( 0xFF0000 );
p = Point.polar( 20, 0 * Math.PI / 180 ).add( center );
s.x = p.x;
s.y = p.y;
s.z = 20;
bubbles.push( s );
s = createCircle( 0x00FF00 );
p = Point.polar( 20, 120 * Math.PI / 180 ).add( center );
s.x = p.x;
s.y = p.y;
s.z = 20;
bubbles.push( s );
s = createCircle( 0x0000FF );
p = Point.polar( 20, 240 * Math.PI / 180 ).add( center );
s.x = p.x;
s.y = p.y;
s.z = 20;
bubbles.push( s );
addEventListener( Event.ENTER_FRAME, ReorderChildren );
function createCircle( c:int ):Sprite
     var s:Sprite = new Sprite();
     s.graphics.beginFill( c );
     s.graphics.drawCircle( 0, 0, 20 );
     s.graphics.endFill();
     return s;
function ReorderChildren( event:Event )
     //bubbles.sort( highFirst );
     bubbles.sort( lowFirst );
     //bubbles.sort(function compare(x:Sprite, y:Sprite):int { return y.z - x.z; });
     for (var ind:int = 0; ind < bubbles.length; ind++)
          addChild(bubbles[ind]);
          trace( bubbles[ind].z );
// higest value first in array
function highFirst(a:Sprite, b:Sprite):int
     if( a.z > b.z )
             return 1;
     else if ( a.z < b.z )
             return -1;
     else
          return 0;
// higest value first in array
function lowFirst(a:Sprite, b:Sprite):int
     if( a.z < b.z )
             return 1;
     else if ( a.z > b.z )
             return -1;
     else
          return 0;
If you wish to have a go.
Kind regards,
Manno