function openwin(url,width,height) {
	if (!width) width = 400;
	if (!height) height = 200;
	var newwin = null;
	LeftPosition = (screen.width) ? (screen.width-width)/2 : 0;
	TopPosition = (screen.height) ? (screen.height-height)/2 : 0;
	newwin = window.open(url,"newwin","width="+width+",height="+height+",resizable,scrollbars,left="+LeftPosition+",top="+TopPosition+"");
}