Abstract: The present invention relates to a computer system having a user interface through which a user can select an action in order to invoke a desired operation, and to a method of operation of such a computer system. The action is selectable by one or more views provided via the user interface, and the system comprises generation means for representing an action by an action object, the action object defining, for each available view that can be employed to represent that action, the attributes required to provide that view, and an identifier to identify the operation to be invoked upon selection of the action. Further the system comprises identifying means for identifying when a user selection of a view has occurred, and for informing the associated action object of that selection, and the action object is responsive to the identifying means to employ the unique identifier to generate a command to invoke the desired operation.