// Define private variable for maxFontSize. public var _maxFontSize:Number = 15; // Define public getter method, mark the property // as usable for the source of data binding, // and specify the name of the binding event. [Bindable("maxFontSizeChanged")] public function get maxFontSize():Number { return _maxFontSize; } // Define public setter method. public function set maxFontSize(value:Number):void { if (value <= 30) { _maxFontSize = value; } else _maxFontSize = 30; // Dispatch the event to trigger data binding. dispatchEvent(new Event("maxFontSizeChanged")); }