ok here is what i want to do.i made i site but it scales by display screen and when display screen is to big e.g 1440x900 the quality is not so good.i whant when display screen is biger than 1280x768 to automatic stage go to
Stage.scaleMode = "noScale";
and if it is low than 1280x768 set to
Stage.scaleMode = "Scale";
can anyone helps ?
i tride this but dont works 
i dont know as but i tryde 
if (stage._x>1280){
Stage.scaleMode = "noScale";
}
else Stage.scaleMode = "Scale";