function popup_login (url, h, w, extras) {
	// initilize variables
	var props = "resizable=no,scrollbars=auto,status=yes,toolbar=no,menubar=no";
	// append the list of properties to the default properties
	if ( extras != "" ) {
		props += ","+ extras;
	}
	// require a height and width to be specified
	if ( w == "" || h == "" ) {
		return false;
	} else {
		// open the Pop-up Login window
		popupLogin = window.open(url, "popupLogin","width="+ w +",height="+ h +","+ props);
	}
}