Código :
var mc:MovieClip;
var flag:Boolean=false;
var desplazar:Function;
var velocidad:Number=5;
//var intervalo:Function;
desplazar=function(mc:MovieClip,eje:String,pixeles:Number):Void{
mc["_"+eje]+=pixeles;
updateAfterEvent();
}
mc.onKeyDown =function(){
if(flag==false){
flag=true;
if(Key.isDown(Key.RIGHT)){
intervalo=setInterval(desplazar,10,this,"x",velocidad);
}else if(Key.isDown(Key.LEFT)){
intervalo=setInterval(desplazar,10,this,"x",-velocidad);
}else if(Key.isDown(Key.UP)){
intervalo=setInterval(desplazar,10,this,"y",-velocidad);
}else if(Key.isDown(Key.DOWN)){
intervalo=setInterval(desplazar,10,this,"y",velocidad);
}
}
}
mc.onKeyUp=function(){
flag=false;
clearInterval(intervalo);
}
key.addListener(mc);