[ommm]

подробнее:

import mx.controls.Alert;
import mx.events.FlexEvent;
 
private var mainContextMenu:ContextMenu = new ContextMenu();
private var about:ContextMenuItem;
 
protected function init(event:FlexEvent):void
{
	about = new ContextMenuItem("О программе");
	about.addEventListener(ContextMenuEvent.MENU_ITEM_SELECT, showAbout);
	mainContextMenu.hideBuiltInItems();
	mainContextMenu.customItems.push(about);
	this.contextMenu = mainContextMenu;
}
 
protected function showAbout(event:ContextMenuEvent):void
{
	Alert.show("Мы супер пупер", "О программе:");
}