Scrolling image on stage goes to far

Hi I am going to be implementing this into a full screen flash site and if you initially bring this site up with your window maximized, the image scrolls to far on the X axis as in you can see the white background behind it. If you resize the stage and scroll, you can see the white on the Y axis. Can someone help me figure out how to make it so it doesnt go past the MC?

here is my code so far:

fscommand("fullscreen", "true");
var scrollableX:Number = content._width-Stage.width;
var scrollableY:Number = content._height-Stage.height;
var percentX:Number = 0;
var percentY:Number = 0;
var startX:Number = content._width/2;
var startY:Number = content._height/2;
//var endRotationX : Number = content._rotation + 5;
var cw:Number = content._width;
var ch:Number = content._height;
content.onEnterFrame = contentScroll;

function contentScroll():Void {
    percentX = _xmouse/Stage.width;
    percentY = _ymouse/Stage.height;
    this.newX = startX-(scrollableX*percentX);
    this.newY = startY-(scrollableY*percentY);
    //this.newR = (endRotationX*2) * percentX - endRotationX;
    //this._rotation += (this.newR-this._rotation)*0.1;
    this._x += (this.newX-this._x)*0.1;
    this._y += (this.newY-this._y)*0.1;

var stageSizeListener:Object = new Object();
stageSizeListener.onResize = function() {
    var sw = Stage.width;
    var sh = Stage.height;
    content._width = cw+sw;
    content._height = ch+sh;