function getPageScroll()
{
	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;
}

function getPageSize()
{	
	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;
}

function popupShow(cover, popup)
{
	var elemCover 	= document.getElementById(cover);
	var elemPopup 	= document.getElementById(popup);
	
	var pageSize 	= getPageSize();
	var pageScroll 	= getPageScroll();
	
	elemCover.style.width 		= '100%';
	elemCover.style.height 		= (pageSize[1] + 'px');
	elemCover.style.visibility	= 'visible';

	var elemPopupTop 	= pageScroll[1] + ((pageSize[3] - elemPopup.offsetHeight) / 2);
	var elemPopupLeft 	= ((pageSize[0] - elemPopup.offsetWidth) / 2);
		
	elemPopup.style.top  = (elemPopupTop < 0) ? '0px' : elemPopupTop + 'px';
	elemPopup.style.left = (elemPopupLeft < 0) ? '0px' : elemPopupLeft + 'px';

	elemPopup.style.visibility = 'visible';
	
	pageSize = getPageSize();
	elemCover.style.height = (pageSize[1] + 'px');
}

function popupHide(cover, popup)
{
	var elemCover 	= document.getElementById(cover);
	var elemPopup 	= document.getElementById(popup);
	
	elemCover.style.visibility 	= elemPopup.style.visibility = 'hidden';
}