Sorry I misunderstood your earlier question. Yes, it is strange that running a SWF on its own and loading it into a host SWF yields different results. However, think of it this way – when you run a SWF directly on its own, the top level display object is the top level class (so stage is not NULL) whereas loading a SWF as a module is a two step process (instantiating the class as a display object, then adding it as the child of the Loader object).

I wished Adobe would actually design the player API such that stage is always defined (it should, since there is only ever going to be just one stage). Stage really should be a globally accessible object that always point to the top level display object, but unfortunately it isn’t.

Even in standalone mode, in constructor context, the flash object still not fully created, so it is not added to stage, still get null reference to stage. Right?

this.addEventListener(Event.ADDED_TO_STAGE, init, false, 0, true )
function init(event:Event):void {
trace(MovieClip(this.parent.parent));
// calls to main timeline will now work
}