PAPERS CHI 97 * 22-27 MARCH 1997 Elastic Windows: Evaluation of Multi-Window Operations Eser Kandogan and Ben Shneiderman* Department of Computer Science, Human-Computer Interaction Laboratory *Institute for Systems Research University of Maryland, College Park, MD 20742 [email protected]. edu, [email protected] ABSTRACT ● Independent control of multiple programs Most windowing systems follow the independent overlap- ● Reminding ping windows approach, which emerged as an answer to ● Command contexthctive forms the needs of the 1980s’ technology. Due to advances in ● Multiple representations computers and display technology, and increased informa- Most current windowing systems follow the independent tion needs, modem users demand more functionality from overlapping windows approach, which emerged as an answer window management systems. We proposed Elastic Win- to the needs of 1980’s applications and technology. These dows with improved spatial layout and rapid multi-window windowing systems no longer provide efficient means to serve operations as an alternative to current window management the functions in this list for today’s information-intensive ap- strategies for efficient personal role management [12]. In this plications. Whh advances in computer networks, especially approach, multi-window operations are achieved by issurng the Internet, users are collecting more information in image, operations on window groups hierarchically organized in a video, sound, and structured text formats. space-filling tiled layout. ‘l%is paper describes the Elastic Windows interface briefly and then presents a study compar- With the introduction of windows, users can employ spatial ing user performance with Elastic Windows and traditional attributes like location of icons or open windows to access window management techniques for 2, 6, and 12 window information. However, current systems provide limited capa- situations. Elastic Whdows users had statistically signifi- bilities of icon and window organization; generally a single cantly faster performance for all 6 and 12 window situations, screen space where icons and windows can be placed inde- for task environment setup, task environment switching, and pendently anywhere on the scrwxs. As a result, the computer task execution. For some tasks there was a ten-fold speed-up screen becomes cluttered and windows are hidden, making it in performance These results suggest promising possibili- harder to access information using spatial attributes. ties for multiple window operations and hierarchical nesting, which can be applied to the next generation of tiled as well Access to and use of multiple sources of information or mul- as overlapped window managers. tiple representations are difficult because operations are per- formed one window at a time. Providing multiple window Keywords operations with a single action is likely to help users. Window Management, Multi-window operations, Personal Role Management, Tiled Layout, User Interfaces, Informa- Novel approaches emphasize a docu-centric approach (Mi- tion Access and Organization. crosoft OLE and Apple’s OpenDoc ) in which documents become more important and applications fade into the back- INTRODUCTION ground. The enriched document can contain various types of As Card et al. [5] stated, an analysis of window management objects such as text, image, video, sounds, spreadsheets, etc. strategies can only be done by a careful consideration of the tasks for which windows are used. They attempted to Although these innovations are one step toward achieving categorize tasks by the functions provided by windows which a computer working environment in harmony with users’ they listed as: perceptions of their work, an effective organization of infor- mation according to users’ roles that reflects this perception ● More information may bring further benefits [19, 16]. ● Access to multiple sources of information ● Combining multiple sources of information The key to personal role management is organizing infor- mation according to the roles of an individual. When users l’ermission to make dlgitalhwd copies ofal] or pwt of[his ma[erial tbr are working in a role, they have the most relevant objects personal or cliwsroom use is granted wilhout lee provided that the copies regarding that role like schedules, documents, tools, corre- are not made or distributed for prolit or commercial advmtage, the copy- righl notice, lhe Iitle ot’the puhlicalicm and its dzte appear, and notice is spondence with people, etc. all visually available. These gi veil Ihal copyright is hy permission of the ACh4. lx. “I_ocopy otherwise, visual cues remind them of their goals, related individuals, 10 reputrlish. 10 posl on servers or 10 rcdistrilmte to Iisls, requires specitic required tasks, and scheduled events all within the context of permission red/or fee the current role. Users should be able to create and abandon Cl+] 97, Atlanla (;A I ISA roles as well as extend and modify the role hierarchy. Copyright 1997 ACM 0-89791-802-9/97/03 ...$3.50 250 CHI 97 * 22-27 MARCH 1997 PAPERS OfNtmOc map amsdlalbn Figure 1: Hierarchical Organization of a Professor’s Roles: University Research and Teaching, Industry, and Personal Our earlier work [12] stated the requirements for future win- ELASTIC WINDOWS dowing systems. A more complete list is as follows: The Elastic Windows design is based on three principles: hierarchical window organization, multi-window operations, and space-filling tiled layout. , SupP~ a unifi~ framework for information organization and coordination according to users’ roles. Hierarchical Window Organization ● Provide a visual, spatial layout that matches semantics. Hierarchical window organization supports users structuring ● Support multi-window operations for fast arrangement of their work environment according to their roles. It allows information. users to map their role hierarchy onto the nested rectangle ● Support information access with partial knowledge of its tree structure. Hierarchical grouping of windows is indicated nominal, spatial, temporal, and visual attributes and relation- by gradually changing border colors according to the level of ships to other pieces of information. the window (Figure 1). ● Allow fast switching and resumption among roles. ● Free users’ cognitive resources to work on task domain Figure 1 displays the hierarchical organization of different operations rather than computer domain operations. roles of a university professor. This professor is advisor to a ● Use sewen space efficiently and productively for tasks. number of graduate students in a number of research projects, teaches two courses this semester at the university, is liaison to three companies, and has personal duties. The next section gives a brief description of the Elastic Win- dows approach, followed by an analytic comparison of win- The hierarchical layout clearly indicates the hierarchic rela- dowing systems. Next, the study comparing performance tionship between the contents of the windows by the spatial of Elastic Windows to traditional Independent Overlapping cues in the organization of windows. It provides the users Windows is described in detail, along with the results and with an overview of all their roles, where they can pick any observations made. role or parts of it and start working on it. 251 PAPERS CHI 97 k 22-27 MARCH 1997 Figure 2: a) Maximize university roles from Figure 1 Figure 3: a) An empty container window opened on b) Maximize research roles within the university the right b) Multi-window open for selected items Hierarchical grouping provides role-based context for infor- In Elastic Windows, multiple window operations are achieved mation organization. It also supports graphical information by applying the operation to groups of windows at any level hiding capability where window hierarchies can be collapsed of the hierwchy. The results of operations are propagated into a single icon (or other primitives) making the approach to lower level windows inside that group recursively. In this scalable. Collapsed hierarchy of windows can be saved and way, a hierarchy of windows can be packed, resized, or closed retrieved, which allows users to reuse a previous window with a single operation. Operations like multi-window open, organization. Besides, layouts can be saved under different close, resize, maximize, and pack enable users to change the names giving users flexibility in using alternative layouts for window organization quickly to compare, filter, and apply the different subtasks within the same context. information. Current window management strategies have a limited no- In Elastic Windows, window groups can be created by open- tion of workspace. Most of the systems provide only one ing a container window and dragging and dropping selected screen, whereas more novel systems, following the Rooms items inside this window (Figure 3). Separate windows are approach [11 ], provide multiple virtual screen spaces where opened for each item in the selection as a member of the group windows can be placed in any of these spaces. Rooms also surrounded by the container-window borders. Multiple items provides an overview where users can look at thumbnail im- can be added to or removed from the group at any time. It is ages of the screen layouts and use the overview to switch to also possible to open a new container window within another these screens. Users are limited to an overview level and the container window to create hierarchical windows. workspace level.