function popup(url, theWidth, theHeight) {
	var winLeft = (screen.width-theWidth)/2;
	var winTop = (screen.height-theHeight)/2;
	var theWindow = window.open(url, 'theWindow', 'menubar=no,location=no,resizable=no,scrollbars=no,status=no,width='+theWidth+',height='+theHeight+',left='+winLeft+',top='+winTop);
	
    if (!theWindow.closed && theWindow.location) {
    	theWindow.focus();
    }
}