function popup_centre(page) {
	var winl = (screen.width - 900) / 2; var wint = (screen.height - 720) / 2;
	win = window.open(page,'site','width=900,height=720,top='+wint+',left='+winl+',toolbar=no,directories=no,status=no,menubar=no,resizable=no,scrollbars=no,align=center')
	if(parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}