function open_window(url,width,height) {
	window.open(url,'_blank','toolbar=0,location=0,directories=0,status=1,menubar=0,scrollbars=yes,resizable=yes,width='+width+',height='+height+',top='+(window.screen.height/2 - height/2)+',left='+(window.screen.width/2 - width/2));
}