function popWin(winurl, winname, width, height)
{
	var w = ((width != null) ? width : '800');
	var h = ((height != null) ? height : '600');

	x = (640 - w)/2, y = (480 - h)/2;

	if (screen)
	{
		y = (screen.availHeight - h)/2;
		x = (screen.availWidth - w)/2;
	}

	newwin = window.open(winurl,winname,'width='+w+',height='+h+',screenX='+x+',screenY='+y+',top='+y+',left='+x+',channelmode=0,dependent=1,directories=0,fullscreen=0,location=0,menubar=0,resizable=0,scrollbars=0,status=0,toolbar=0');
	newwin.focus();
	return newwin;
}