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
kandogan@cs.umd.edu, ben@cs.umd.edu
ABSTRACT
Most windowing systems follow the independent overlap-
ping windows approach, which emerged as an answer to
the needs of the 1980s’ technology. Due to advances in
computers and display technology, and increased informa-
tion needs, modern users demand more functionality from
window management systems. We proposed Elastic Win-
dows with improved spatial layout and rapid multi-window
operations as an alternative to current window management
strategies for efficient personal role management [12]. In this
approach, multi-window operations are achieved by issuing
operations on window groups hierarchically organized in a
space-filling tiled layout. This paper describes the Elastic
Windows interface briefly and then presents a study compar-
ing user performance with Elastic Windows and traditional
window management techniques for 2, 6, and 12 window
situations. Elastic Windows users had statistically signifi-
cantly faster performance for all 6 and 12 window situations,
for task environment setup, task environment switching, and
task execution. For some tasks there was a ten-fold speed-up
in performance. These results suggest promising possibili-
ties for multiple window operations and hierarchical nesting,
which can be applied to the next generation of tiled as well
as overlapped window managers.
Keywords
Window Management, Multi-window operations, Personal
Role Management, Tiled Layout, User Interfaces, Informa-
tion Access and Organization.
INTRODUCTION
As Card et al. [5] stated, an analysis of window management
strategies can only be done by a careful consideration of
the tasks for which windows are used. They attempted to
categorize tasks by the functions provided by windows which
they listed as:
 More information
 Access to multiple sources of information
 Combining multiple sources of information
 Independent control of multiple programs
 Reminding
 Command context/active forms
 Multiple representations
Most current windowing systems follow the independent
overlapping windows approach, which emerged as an answer
to the needs of 1980’s applications and technology. These
windowing systems no longer provide efficient means to serve
the functions in this list for today’s information-intensive ap-
plications. With advances in computer networks, especially
the Internet, users are collecting more information in image,
video, sound, and structured text formats.
With the introduction of windows, users can employ spatial
attributes like location of icons or open windows to access
information. However, current systems provide limited capa-
bilities of icon and window organization; generally a single
screen space where icons and windows can be placed inde-
pendently anywhere on the screen. As a result, the computer
screen becomes cluttered and windows are hidden, making it
harder to access information using spatial attributes.
Access to and use of multiple sources of information or mul-
tiple representations are difficult because operations are per-
formed one window at a time. Providing multiple window
operations with a single action is likely to help users.
Novel approaches emphasize a docu-centric approach (Mi-
crosoft OLE and Apple’s OpenDoc ) in which documents
become more important and applications fade into the back-
ground. The enriched document can contain various types of
objects such as text, image, video, sounds, spreadsheets, etc.
Although these innovations are one step toward achieving
a computer working environment in harmony with users’
perceptions of their work, an effective organization of infor-
mation according to users’ roles that reflects this perception
may bring further benefits [19, 16].
The key to personal role management is organizing infor-
mation according to the roles of an individual. When users
are working in a role, they have the most relevant objects
regarding that role like schedules, documents, tools, corre-
spondence with people, etc. all visually available. These
visual cues remind them of their goals, related individuals,
required tasks, and scheduled events all within the context of
the current role. Users should be able to create and abandon
roles as well as extend and modify the role hierarchy.

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-
dowing systems. A more complete list is as follows:
 Support a unified framework for information organization
and coordination according to users’ roles.
 Provide a visual, spatial layout that matches semantics.
 Support multi-window operations for fast arrangement of
information.
 Support information access with partial knowledge of its
nominal, spatial, temporal, and visual attributes and relation-
ships to other pieces of information.
 Allow fast switching and resumption among roles.
 Free users’ cognitive resources to work on task domain
operations rather than computer domain operations.
 Use screen space efficiently and productively for tasks.
The next section gives a brief description of the Elastic Win-
dows approach, followed by an analytic comparison of win-
dowing systems. Next, the study comparing performance
of Elastic Windows to traditional Independent Overlapping
Windows is described in detail, along with the results and
observations made.
ELASTIC WINDOWS
The Elastic Windows design is based on three principles:
hierarchical window organization, multi-windowoperations,
and space-filling tiled layout.
Hierarchical Window Organization
Hierarchical window organization supports users structuring
their work environment according to their roles. It allows
users to map their role hierarchy onto the nested rectangle
tree structure. Hierarchical grouping of windows is indicated
by gradually changing border colors according to the level of
the window (Figure 1).
Figure 1 displays the hierarchical organization of different
roles of a university professor. This professor is advisor to a
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 hierarchical layout clearly indicates the hierarchic rela-
tionship between the contents of the windows by the spatial
cues in the organization of windows. It provides the users
with an overview of all their roles, where they can pick any
role or parts of it and start working on it.