window.offscreenBuffering=true;

function getWindowWidth() {
    if (typeof(window.innerWidth) == 'number') return window.innerWidth;
    var d = document; 
    var b = d.body ? d.body : d.documentElement;
    return b.clientWidth;
}

function getWindowHeight() {
    if (typeof(window.innerHeight) == 'number') return window.innerHeight;
    var d = document; 
    var b = d.body ? d.body : d.documentElement;
    return b.clientHeight;
}
//alert(getWindowHeight());

function SkyScraper(id, inertia, k, yPad, yMin, yHeight) {

    this.inertia = inertia;
    this.k = k;
    this.yPad = yPad;
    this.yMin = yMin;
    this.yHeight = yHeight;
	
    this.div = document.getElementById ? document.getElementById(id) : document.all[id];
    
    this.yPos = 0;
    this.dy = 0;
	
    this.dest = 0;
    this.lastYOffset = 0;
    this.scrolled = false;

    // global reference to this object
    this.gRef = 'SkyScraper_' + id
    eval(this.gRef+'=this')
    
    if (yPad < yMin) yPad = yMin;
    this.div.style.top = yPad + 'px';

    //alert(getWindowHeight());

    setInterval(this.gRef + '.checkScroll()', 100);
}

SkyScraper.prototype.getPageYOffset = function() {
	if (window.pageYOffset) {
		return window.pageYOffset;
	}
	if (document.body && document.body.scrollTop) {
		return document.body.scrollTop;
	}
	return 0;
}

SkyScraper.prototype.slide = function() {
    var y = this.dest - this.yPos;
	this.dy = this.dy * this.inertia + y * this.k;
    this.yPos += this.dy; 
    this.div.style.top = Math.round(this.yPos) + 'px';
    if (Math.round(this.dy) != 0) {
    	setTimeout(this.gRef + '.slide()', 100);
    }
}

SkyScraper.prototype.checkScroll = function() {
	var y = this.getPageYOffset();
	if (y != this.lastYOffset) {
		this.lastYOffset = y;
		this.scrolled = true;
	}
	else if (this.scrolled && this.yHeight < ( getWindowHeight() - 100 ) ) {
		this.scrolled = false;
		this.dest = y + this.yPad;
		if (this.dest < this.yMin) this.dest = this.yMin;
		this.slide();
	}
}