The guidar project aims to support the complete activity of Graphical User Interface Development And Reuse. We propose to organize the system as a collaborative architecture of independent automated agents that actively participate in the design and development process and promote reuse. This paper introduces Concrete Browsing as an improved method of consulting a graphical library, and Spreading Computation as novel paradigm for search and retrieval. A concrete browser allows the user to browse and interact with prototypical instances of graphical components, thus grounding the user's understanding in direct and concrete experience. We have implemented a prototype concrete browser for the garnet toolkit. We also present a combinator-based language with spreading computation semantics for expressing search through graphs of nodes and links such as an object-oriented graphical library. It serves as the mediating layer between the browser, and eventually all agents, and the library...