It is widely believed that windowed environments are superior to non-windowed ones. However, an early study by Bury et al.  (1985) comparing users' performance in windowed systems to non-windowed systems revealed that task-completion time in windowed systems can be longer due to window arrangement time. A detailed analysis, however, showed that actual times spent on solving a task were lower in windowed environments compared to non-windowed environments. Their experiments also showed that the error rates in windowed environments were significantly lower. Although systems compared in these experiments were rather old, the results clearly indicate that benefits of windowing can be overshadowed by the extra time spent on window housekeeping activities.
Card et al.  analyzed window usage according to tasks and identified seven functional uses of multiple windows. Among these, independent control of multiple programs, referred to here as multitasking, is the most significant. Basically, it is the ability of users to work on different tasks in separate windows. Analyses of work flow determined that people deal with many tasks concurrently with frequent switches among them . For example, a researcher preparing a paper might draw the figures in one window while writing the text of the document using an editor in another window. Multitasking results in improvements on the overall user performance due to the decreased average task-completion time. Windowing systems must provide good mechanisms for task-switching to make multitasking more beneficial.
Windowing allows access to multiple sources of information. It is possible to reduce the cognitive load on users by allowing them to examine other windows for supplementary information, or multiple representations for the task at hand or use task-aids like cut-and-paste.
As stated by Card et al. , the computer display is used not only as a communication medium but also as an external memory for users. Thus having all the necessary information on the screen and filtering out unnecessary windows is a required property of windowing systems. Malone  observed that the way people organize papers on their desk helps them to structure their work and reminds them of unfinished tasks. As Funke et al.  suggested, windowing systems should support users to integrate, organize, compare, distill, summarize, and apply the information.