1. A method of presenting a customized menu item in a menu display of a media application, the method comprising: receiving one or more application packages from a communications network at a computer system, wherein each application package contains one or more resources for customized application pages of the media application; storing the one or more application packages on the computer system in a storage system external to the media application; accessing internal menu markup data of the media application for rendering a set of menu items for the menu display; determining that the internal menu markup data indicates that the set of menu items for the menu display includes one or more built-in menu items installed with the media application, wherein: the internal menu markup data specifies a reference to a built-in application page of the media application for each built-in menu item, and selection of at least one of the built-in menu items launches a built-in application page that provides functionality for browsing and selecting broadcast television content received by the computer system; determining that the internal menu markup data includes a placeholder for an offering tile for a customized menu item within the set of menu items for the menu display, wherein: the customized menu item provides access to online television content, the placeholder references an application package and a resource for a customized application page, and selection of the offering tile for the customized menu item launches the customized application page to provide functionality for browsing and selecting categories of the online television content; searching for the application package and the resource referenced by the placeholder in the storage system external to the media application; if the application package and the resource referenced by the placeholder are found in the storage system external to the media application: accessing the application package referenced by the placeholder from the storage system external to the media application, accessing the resource referenced by the placeholder from the accessed application package, rendering the one or more built-in menu items and the offering tile for the customized menu item in the menu display of the media application, and customizing display of the offering tile for the customized menu item using content from the resource of the accessed application package; and if the application package and the resource referenced by the placeholder are not found in the storage system external to the media application: rendering the one or more built-in menu items in the menu display of the media application, and setting the offering tile for the customized menu item to be hidden from view.