var Interval;
var popUp;

function showPopup() {
    Interval = window.setInterval("checkScroll()", 500);
    popUp.style.display='block';
}

function hidePopup() {
    clearInterval(Interval);
    popUp.style.display='none';
}

function checkScroll() {
    popUp.style.top = Math.round((document.documentElement.clientHeight/2)-(popUp.style.height/2)+document.documentElement.scrollTop)+'px';
    popUp.style.left = Math.round((document.documentElement.clientWidth/2)-(popUp.style.width/2))+"px";
}


function toggleLayer( whichLayer )
{  
var elem, vis;  
if( document.getElementById ) // this is the way the standards work   
 elem = document.getElementById( whichLayer ); 
  else if( document.all ) // this is the way old msie versions work      
 elem = document.all[whichLayer];  
 else if( document.layers ) // this is the way nn4 works
     elem = document.layers[whichLayer];  
	 vis = elem.style;  // if the style.display value is blank we try to figure it out here  
	 if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)    
	 vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none'; 
	 vis.display = (vis.display==''||vis.display=='block')?'none':'block';
	 

	 
}

	function showFriendPopup() {
		popUp = document.getElementById('sendtoafriend');
	}