/**
 * http://blog.flexexamples.com/2008/07/16/disabling-keyboard-navigation-on-the-combobox-control-in-flex/
 */
package comps {
    import flash.events.KeyboardEvent;
    import mx.controls.ComboBox;

    public class MyComboBoxAS extends ComboBox {
        public function MyComboBoxAS() {
            super();
        }

        override protected function keyDownHandler(event:KeyboardEvent):void {
            // ignore
        }
    }
}