Abstract: A previewing system that permits selection from a plurality of interactive previewers for use in a system shell browser is disclosed. The previews may be extensible, such that different application developers may write custom previews for different file types, and the shell browser may follow established criteria to select an appropriate preview. The user may enter criteria to control which previewers are used for different situations, such as when certain file types are selected for previewing. Size of an available display area for the preview may be a criterion, such that resizing the preview area may cause a different preview to be displayed. The preview may be executed as a separate process from the browser so that crashes and hangs in the previewer process do not fatally affect the browser process. Previews may be incorporated within common file dialogs offered by an underlying operating system, such that different applications may share the common previewer.

Abstract: A navigation tool permits access between separate program modules by communicating state information between each program. By communicating state information between separate program modules, it is possible for a user to access previous screens of data, irrespective of the program module which generated the display, or to advance to previous screens of data if the user has already accessed a previous display. In other words, interactions between separate program modules become seamless in presentation to the user, analogous to how information can be displayed with a internet browser or as if separate program modules were operating under a common shell.