Scroller = {}

Scroller.top = 0;
Scroller.left = 0

Scroller.getPageScroll = function()
{
	var yScroll;

	if (self.pageYOffset) 
	{
	    yScroll = self.pageYOffset;
	} 
	else if (document.documentElement && document.documentElement.scrollTop)
	{
		// Explorer 6 Strict
		yScroll = document.documentElement.scrollTop;
	}
	else if (document.body) 
	{
		// all other Explorers
		yScroll = document.body.scrollTop;
	}

	arrayPageScroll = new Array('',yScroll) 
	return arrayPageScroll;
}

Scroller.getPageSize = function()
{
	var xScroll, yScroll;
	
	if (window.innerHeight && window.scrollMaxY) 
	{	
		xScroll = document.body.scrollWidth;
		yScroll = window.innerHeight + window.scrollMaxY;
	}
	else if (document.body.scrollHeight > document.body.offsetHeight)
	{ 
		// all but Explorer Mac
		xScroll = document.body.scrollWidth;
		yScroll = document.body.scrollHeight;
	} 
	else 
	{ 
		// Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
		xScroll = document.body.offsetWidth;
		yScroll = document.body.offsetHeight;
	}
	
	var windowWidth, windowHeight;
	if (self.innerHeight) 
	{	
		// all except Explorer
		windowWidth = self.innerWidth;
		windowHeight = self.innerHeight;
	} 
	else if (document.documentElement && document.documentElement.clientHeight) 
	{ 
		// Explorer 6 Strict Mode
		windowWidth = document.documentElement.clientWidth;
		windowHeight = document.documentElement.clientHeight;
	} 
	else if (document.body) 
	{ 
		// other Explorers
		windowWidth = document.body.clientWidth;
		windowHeight = document.body.clientHeight;		
	}	
	
	// for small pages with total height less then height of the viewport
	if(yScroll < windowHeight)
	{
		pageHeight = windowHeight;
	} 
	else 
	{ 
		pageHeight = yScroll;
	}

	// for small pages with total width less then width of the viewport
	if(xScroll < windowWidth)
	{	
		pageWidth = windowWidth;
	} 
	else 
	{
		pageWidth = xScroll;
	}

	arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight) 
	return arrayPageSize;
}

Scroller.setPosition = function(item, width, height)
{		
	var arrayPageSize = this.getPageSize();
	var arrayPageScroll = this.getPageScroll();						
	
	this.top = arrayPageScroll[1] + ((arrayPageSize[3] - height) / 2); 			
	this.left = arrayPageScroll[0] + ((arrayPageSize[2] - width) / 2); 

	item.style.left = this.left + "px";
	item.style.top = this.top + "px";	
}