It is difficult to build user interfaces that must be distributed over a set of dynamic and heterogeneous I/O devices. This difficulty increases when we want to split, merge, replicate, and relocate the UI ucross a set of heterogeneous devices, without the applicution intervention. Furthermore, using generic tools, e.g. to search for UI components or to save/restore them, is usually not feasible. We follow a novel approach for building UIs that overcomes these problems: Using distributed file systems that export widgets to applications. In this paper we describe Omero, a UI server built along this line for the Plan B Operating System.