function showBox(w,h) {     
	document.getElementById('overlay').style.display = 'block'; 
	//$('overlay').show();     
	center('xbox', w, h);     
	return false; 
} 

function hideBox() {
	document.getElementById('xbox').style.display = 'none'; 
	document.getElementById('overlay').style.display = 'none'; 
   //  $('xbox').hide();
	// $('overlay').hide();
	 return false; 
} 

function center(element, wd, ht) {
	
	var my_width = screen.width;     
	var my_height = screen.height;   
	var setX = ( my_width - wd ) / 2;     
	var setY = ( my_height - ht ) / 2;   
	
	document.getElementById(element).style.position = 'absolute';     
	document.getElementById(element).style.zIndex = 99;     
	document.getElementById(element).style.left = setX + 'px';     
	document.getElementById(element).style.top = setY + 'px';     
	document.getElementById(element).style.display = 'block'; 
}