Locating the owner of a glass slipper in not the most pressing matter in the Magic Kingdom these days. At the grand opening of a new World of Disney store in New York City, more than 60 members of the Service Trades Council Union that represents workers ranging from ticket-takers to costumed characters at Disney parks and hotels in Florida, handed out leaflets complaining of drawnout negotiations with park officials. Negotiations have been going on for more than six months. The employees are concerned as the contract eliminates some overtime benefits, increases health care costs and eliminates a pension plan for new hires. Disney World spokeswoman Jacquee Polak complained of the protest in New York, saying time would have been better spent at the negotiation table than protesting in a different state.