1. A system for generating a user interface for a web application program, the system comprising: a repository of reusable screen components including graphical user interface (GUI) components stored in a computer-readable medium; means for enabling a user to create a web page layout by: selecting GUI components from the repository, arranging the selected GUI components within the web page, the GUI components being assigned to a specialized class or a non-specialized class; defining interaction between at least two of the selected GUI components, the interaction including causing a first GUI component to perform an action in response to an event generated by a second GUI component, and defining interaction between one or more of the selected GUI components and the web application program, the interaction involving a set of transactions that establish a relationship between properties of the GUI component stored in a database table, business data, and one or more backend systems, wherein establishing the relationship by the set of transactions includes generating the specialized class of GUI components by inheriting the properties specific to the one or more selected GUI components from a super class defined by a user interface framework, wherein the inheriting causes at least one object of a GUI component assigned to a specialized class inherited from the super class to have the same properties as the super class, and further wherein the GUI components assigned to the non-specialized class do not inherit the properties of the super class; and means for storing rendering information of the web page layout to enable a web server to render the web page.