// JavaScript Document

window.onscroll = function(e)
{

	var bg_scr = $('back_screen');
	if(bg_scr)
	{
		
		bg_scr.style.top = getScrollTop()+"px";
	}
}

function getScrollTop()
{
	if (window.pageYOffset){  
		scrollTop = window.pageYOffset 
	} else if(document.documentElement && document.documentElement.scrollTop){ 
		scrollTop = document.documentElement.scrollTop; 
	} else if(document.body){ 
		scrollTop = document.body.scrollTop; 
	} 
	return scrollTop;
}


function close_backscreen()
{
	var itm = $('back_screen');
	if(itm)itm.parentNode.removeChild(itm);
}

function show_backscreen()
{
	try
	{
		if(window.innerHeight){ 
			windowHeight=window.innerHeight; 
		} else if(document.documentElement && document.documentElement.clientHeight){ 
			windowHeight=document.documentElement.clientHeight; 
		} else if(document.body){ 
			windowHeight=document.body.clientHeight; 
		}
	
		var back = 	document.createElement("div");
		back.id = "back_screen";
		back.className = "back_screen";
		back.style.height = windowHeight;
		back.style.top =  getScrollTop()+"px";
		document.body.appendChild(back);	
	}catch(e){
	}
}