function Menu(id) {
        this.id = id;
    }
Menu represents a top-level menu in the menu bar. A Menu may correspond to an HTML-based
menu or a native menu if Brackets is running in a native application shell.

Since menus may have a native implementation clients should create Menus through
addMenu() and should NOT construct a Menu object directly.
Clients should also not access HTML content of a menu directly and instead use
the Menu API to query and modify menus.

@constructor
@private

@param {string} id