AS3: addChild()

Question

I'm just getting into AS3 and it is making me crazy. All over
the place (help files etc.) I see code like this.
addChild(myLoader);
Where myLoader is an instance of the Loader class. But it
could be a Sprite or something else. But to what are we adding the
child? It seems that Loader inherits like this (has anybody else
noticed that copying from the help files never seems to work on the
first try?):
Loader DisplayObjectContainer InteractiveObject DisplayObject
EventDispatcher Object
And it seems that addChild() is inherited from the
DisplayObjectContainer class. So is the addChild adding the loader
to itself?

Answer 1

When you create a DisplayObject using the new operator, it
has no parent.
The addChild method allows you to change the objects
parentage -- a real
improvement for Flash.
Try this snippet in the timeline:
import flash.display.*;
import flash.events.MouseEvent;
var s1:Sprite = new Sprite();
var s2:Sprite = new Sprite();
s1.x = 10;
s1.y = 10;
s2.x = 200;
s2.y = 10;
this.addChild(s1);
this.addChild(s2);
var rect:Shape = new Shape();
rect.graphics.beginFill(0xff0000);
rect.graphics.drawRect(0,0,100,100);
rect.graphics.endFill();
rect.x = 20;
rect.y = 20;
s2.addChild(rect);
s2.addEventListener(MouseEvent.CLICK, clickHandler);
s1.addEventListener(MouseEvent.CLICK, clickHandler);
function clickHandler(event:MouseEvent){
if(event.target == s1){s2.addChild(rect);}
else{s1.addChild(rect);}
trace(rect.parent.name)