function myPopup(windowName, URL, width, height, scrolling) {
	width = width || 500;
	height = height || 460;
	scrolling = scrolling || 0;
	
	var topX = (window.screen.width / 2) - ( width / 2);
	var topY = (window.screen.height / 2) - ( height / 2);
	
	window.open(URL, windowName, 'width=' + width + ',height=' + height +
 ',location=no,resizable=yes,scrollbars=' + scrolling + 
',screenX=' + topX + ',screenY=' + topY);
}