1. A method of processing user input to a computing system, the method comprising: accessing a business service property of a data structure stored within the computing system, wherein the data structure is associated with selection by a user of a user interface item, a method property of the data structure is adapted to identify a specified method to be invoked when the user interface item is selected, and the business service property is adapted to identify a specified service running within the computing system for handling the invoking of the specified method, if such a service has been specified; determining that no specified service is identified by the business service property; and in response to the determining, selecting a method handler routine, wherein the selecting is based at least in part on a level of the user interface item within a user interface presented by an application program running within the computing system.