MOSTLY COMPLETE DRAFT ! Last updated: 4 December 2002
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Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user. [Priority 2]
Web Content Accessibility Guidelines 1.0 (http://www.w3.org/TR/WCAG/)
Usability studies show that novice users (including those without disabilities) often do not understand the concept of stacked windows and think only one window is open at a time. They can be confused with multiple windows. Another potential problem is that opening new windows "breaks" the browser's Back button, or previous page functionality.
Many browser provide functionality for users to open links in new windows themselves. For example, in Internet Explorer, if you right mouce click on a link, you can select "Open in New Window" from the pop-up menu. This option is also "broken" by some ways of making the link open a new browser window.
Sometimes when a new window is opened, the user will look at the new window, and then go back to the first window without closing the second. The first window then sends new information to the second window but the user does not see the update because the second window doesn't get focus if it's already created. In such a case, the user will often think the site is broken.
While most screen readers will automatically shift focus to a new window, they don't inform the user that the window changed. Therefore, non-visual users may not know that a new window was opened. This can lead to significant confusion, and render the web site unusable.
Checkpoint 10.1 does not prohibit spawned windows; rather, it requires that users be informed of them. There are several options for informing users of spawned windows.
One option for informing the user of a new window is to inform them with the action that opens the new window, with either text or an icon with ALT text.
While the options shown above have the advantage of informing the user before the action is taken, both add a bit of visual clutter to the rendered page.
Another option is to inform the user in the spawned window itself and in any instructions or site help.
There are good reasons to use spawned windows, such as to provide help for a form without losing data and context. However, because of the drawbacks to spawned windows (addressed in Accessibility and Usability Issues above), they should be used only when there is a compelling reason that outweighs the disadvantages.
In cases where a spawned window is warrented, there are several things that you can do to help users recognize that it is a new browser window. Pop-up dialog boxes are familiar to graphical user interface users, and this metaphor can be uses