Setting X and Y limitations

programming flash
1

Hi

I currently have a script that allows the user to click on a right or left arrow to scroll across a movie under a mask, but currently they can scroll it so you don’t see anything in the middle. How can I add an X and Y axis limitations so this doesnt happen to the following script:

var move_fn:String="";
var speed:Number = 5;

left_arrow.onRelease=right_arrow.onRelease=function(){
move_fn=""
}
left_arrow.onPress=function(){
move_fn="left"
}
right_arrow.onPress=function(){
move_fn="right"
}
this.onEnterFrame=function(){
if(move_fn=="left"){
object_mc._x-=speed;
}
if(move_fn=="right"){
object_mc._x+=speed;
}
}

Thanks

Eddie