function show_popup(URL, wname, wwidth, wheight)
{
	var wleft = (screen.width-wwidth)/2;
	var wtop = (screen.height-wheight)/2;
	window.open(URL, wname, 
		'toolbar=no,location=no,titlebar=yes,status=yes,menubar=no,'+
		'resizable=no,copyhistory=no,scrollbars=yes,'+
		'width='+wwidth+',height='+wheight+',top='+wtop+',left='+wleft);
}
function image_popup(URL, wwidth, wheight)
{
	return show_popup(URL, '_blank', wwidth + 50, wheight + 50);
}