Method and system for providing an extensible user interface

Displaying a custom user interface in response to a determination that the application program is configured to display the custom user interface. To create the custom user interface, the end user can customize one or more default user interface files to create custom user interface files. The default user interface files can comprise one or more of a structure definition file, a content definition file, and a content display file. Additionally, the custom user interface can be associated with a program module function that can execute in connection with displaying the custom user interface.