1. A method of customizing a customizable theme of a user interface of a computer system, the method comprising the steps of: receiving a base theme comprising a plurality of layers, each of said layers comprising at least one object, at least some of said at least one object having one or more graphical properties; mapping each of a plurality of screens for the user interface to each of said layers, each of said screens having at least one screen attribute associated therewith; mapping each respective screen attribute to the graphical properties related to the respective screen attribute, said mapped screens and screen attributes defining the customizable theme of the user interface; receiving a user input to modify said at least one screen attribute corresponding to a first screen to customize the customizable theme; and modifying the graphical properties related to the modified screen attribute.