Modern Information Retrieval Chapter 10: User Interfaces and Visualization

Contents

   
2. Window Management

interface design!window management window management

For search tasks more complex than the simple string matching find operations described above, the interface designer must decide how to lay out the various choices and information displays within the interface.

As discussed above, traditional bibliographic search systems use TTY-based command-line interfaces or menus. When the system responds to a command, the new results screen obliterates the contents of the one before it, requiring the user to remember the context. For example, the user can usually see only one level of a subject hierarchy at a time, and must leave the subject view in order to see query view or the document view. The main design choices in such a system are in the command or menu structure, and the order of presentation of the available options.

In modern graphical interfaces, the windowing system can be used to divide functionality into different, simultaneously displayed views [#!myers88!#]. In information access systems, it is often useful to link the information from one window to the information in another, for example, linking documents to their position in a table of contents, as seen in SuperBook . Users can also use the selection to cut and paste information from one window into another, for example, copy a word from a display of thesaurus terms and paste the word into the query specification form.=-1

interface design!monolithic window layout monolithic window layout interface design!tiled windows tiled windows

When arranging information within windows, the designer must choose between a monolithic display, in which all the windows are laid out in predefined positions and are all simultaneously viewable, tiled windows , and overlapping windows . User studies have been conducted comparing these options when applied to various tasks [#!shneiderman97!#,#!billingsley88!#]. Usually the results of these studies depend on the domain in which the interface is used, and no clear guidelines have yet emerged for information access interfaces.

The monolithic interface has several advantages. It allows the designer to control the organization of the various options, makes all the information simultaneously viewable, and places the features in familiar positions, making them easier to find. But monolithic interfaces have disadvantages as well. They often work best if occupying the full viewing screen, and the number of views is inherently limited by the amount of room available on the screen (as opposed to overlapping windows which allow display of more information than can fit on the screen at once). Many modern work-intensive applications adopt a monolithic design, but this can hamper the integration of information access with other work processes such as text editing and data analysis. Plaisant et al. [#!plaisant95!#] discuss issues relating to coordinating information across different windows to providing overview plus details.

A problem for any information access interface is an inherent limit in how many kinds of information can be shown at once. Information access systems must always reserve room for a text display area, and this must take up a significant proportion of screen space in order for the text to be legible. A tool within a paint program, for example, can be made quite small while nevertheless remaining recognizable and usable. For legibility reasons, it is difficult to compress many of the information displays needed for an information access system (such as lists of thesaurus terms, query specifications, and lists of saved titles) in this manner. Good layout, graphics, and font design can improve the situation; for example, Web search results can look radically different depending on spacing, font, and other small touches [#!mullet95!#].

interface design!overlapping windows overlapping windows

Overlapping windows provide flexibility in arrangement, but can quickly lead to a crowded, disorganized display. Researchers have observed that much user activity is characterized by movement from one set of functionally related windows to another. Bannon et al. [#!bannon83!#] define the notion of a workspace -- the grouping together of sets of windows known to be functionally related to some activity or goal -- arguing that this kind of organization more closely matches users' goal structure than individual windows [#!billingsley88!#]. Card et al. [#!card84!#] also found that window usage could be categorized according to a `working set' model. They looked at the relationship between the demands of the task and the number of windows in use, and found the largest number of individual windows were in use when users transitioned from one task to another.

interface design!workspaces workspaces interface design!rooms rooms

Based on these and other observations, Henderson and Card [#!hendersen86!#] built a system intended to make it easier for users to move between `multiple virtual workspaces' [#!billingsley88!#]. The system uses a 3D spatial metaphor, where each workspace is a `room,' and users transition between workspaces by `moving' through virtual doors. By `traveling' from one room to the next, users can change from one work context to another. In each work context, the application programs and data files that are associated with that work context are visible and readily available for reopening and perusal. The workspace notion as developed by Card et al. also emphasizes the importance of having sessions persist across time. The user should be able to leave a room dedicated to some task, work on another task, and three days later return to the first room and see all of the applications still in the same state as before. This notion of bundling applications and data together for each task has since been widely adopted by window manager software in workstation operating system interfaces.

interface design!elastic windows elastic windows

Elastic windows  [#!kandogan97a!#] is an extension to the workspace or rooms notion to the organization of 2D tiled windows. The main idea is to make the transition easier from one role or task to another, by adjusting how much of the screen real estate is consumed by the current role. The user can enlarge an entire group of windows with a simple gesture, and this resizing automatically causes the rest of the workspaces to reduce in size so they all still fit on the screen without overlap.=-1