1. A method of generating an association between a software object and a sticker on a surface, and retrieving said software object, the method including, in a computer system, the steps of: providing the sticker having disposed therein or thereon coded data at least partially indicative of a sticker identity; receiving indicating data from a sensing device, the sensing device being responsive to sensing at least part of the coded data in order to determine the sticker identity, the indicating data being at least partially indicative of the sticker identity; storing object data indicative of each of a plurality of software objects in an object repository; ordering the object data stored in the object repository according to when the software object data was stored in the object repository; determining, using the order of the object data in the object repository, the software object which has been most recently stored in the object repository; generating the association based at least partially on the most recently stored software object and the sticker identity; receiving further indicating data from the sensing device, the indicating data being at least partially indicative of the sticker identity; and retrieving the software object associated with the sticker identity.