package com.neonsunburst {
	
    import flash.events.*;
    
	public class Model extends EventDispatcher {

		public static var totalPages:int;
		public static var currentPage:int;
		public static var previousPage:int;

		function Model() {
			totalPages = 3;
			currentPage = 1;
		}
		function setCurrentPage(p:int) : void {
				previousPage = currentPage;
				currentPage = p; 
				trace (this + " currentPage is " + currentPage); 
				trace (this + " previousPage is " + previousPage); 
				dispatchEvent(new Event(Event.CHANGE));
		}
		function getCurrentPage() : int {
			return currentPage;
		}
		function getPreviousPage() : int {
			return previousPage;
		}
		function getTotalPages() : int {
			return totalPages;
		}
		
		
	}
}

package com.neonsunburst {
	
    import flash.events.*;
    
	public class Model extends EventDispatcher {

		public static var totalPages:int;
		public static var currentPage:int;
		public static var previousPage:int;

		function Model() {
			trace ("model");
			totalPages = 3;
			currentPage = 1;
		}
		function setCurrentPage(p:int) : void {
				previousPage = currentPage;
				currentPage = p; 
				trace (this + " currentPage is " + currentPage); 
				trace (this + " previousPage is " + previousPage); 
				dispatchEvent(new Event(Event.CHANGE));
		}
		function getCurrentPage() : int {
			return currentPage;
		}
		function getPreviousPage() : int {
			return previousPage;
		}
		function getTotalPages() : int {
			return totalPages;
		}
		
		
	}
}

neonsunburst.com

The singleton model extends EventDispatcher and fires events when it is updated by the controller.

Neonsunburst Model Class

actionscript

ActionScript 3