function centeropen(url, winwidth, winheight)
	{
 		var centerwin=window.open(url, "", "toolbar=0, resize=0, scrollbars=0, status=1")
 		centerwin.resizeTo(winwidth, winheight)
 		centerwin.moveTo(screen.width/2-winwidth/2, screen.height/2-winheight/2) //center window on user's screen
	}