import flash.events.Event;
    import flash.events.EventDispatcher;
    import flash.events.IEventDispatcher;
	
    public class Dispatcher implements IEventDispatcher {
		
		private static var instance : EventDispatcher = new EventDispatcher();
        
        public function Dispatcher() {            
			if (instance) {
				throw new Error( "Dispatcher and can only be accessed through Dispatcher.getInstance()" ); 
			}
        }
		
		public static function getInstance() : EventDispatcher {
			return instance;
		}
        
        /* Miembros de flash.events.IEventDispatcher */
        
        public function addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, 
			useWeakReference:Boolean = false):void{
            instance.addEventListener(type, listener, useCapture, priority, useWeakReference);
        }
        
        public function dispatchEvent(event:Event):Boolean {            
            return instance.dispatchEvent(event);
        }
        
        public function hasEventListener(type:String):Boolean { 
			return instance.hasEventListener(type);
        }
        
        public function removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void{
            instance.removeEventListener(type, listener, useCapture);
        }
        
        public function willTrigger(type:String):Boolean{
            return instance.willTrigger(type);
        }
    }

Global dispatcher AS3

ActionScript 3