A change of user agent, viewport, user interface controls, or focus; or complete change of content.
Editorial Note: the definition of “change of context” is still under discussion. "user interface controls" is removed from the definition above, based on standard form control show/hide behavior practice such as Gez's example.
The intent of this success criterion is avoid confusion that could be caused by certain specific changes in the user agent or the content which the user cannot infer from his own interaction with the content. For example, people may get confused if a new window opens if they did not request this. They may also get confused if the browser loads a new document without their request, for example as the result of selecting an item from a drop-down list without submitting this choice (possibly because they changed their mind).
Further below is a description of who benefits from this success criterion.
For auto-refreshing content:
Editorial Note: Timeouts are covered by covered by Guideline 2.2 L1 SC1, but WCAG 1.0 Checkpoint 7.4 (auto-refreshing pages) also maps to Guideline 3.2 L3 SC2.
For automatic redirects:
For pop-up windows:
Editorial Note: These techniques have not been written yet.
Provide automatic redirects by …
If you cannot use server-side redirects, implement automatic redirects by …
If you cannot use server-side redirects, implement automatic redirects by …
Editorial Note: Meta redirect with a timeout is not allowed by this success criterion. However, at Level 1, it is covered by Guideline 2.2 L1 SC1.
Open new windows by …
target attribute instead of scripts,.
indicating that the link may open in a new window,
or
target attribute, because many user agents allow users to open links in another window or tab.
Editorial Note: This technique is currently mapped to Guideline 3.2 L1 SC1, but there is a proposal to remove this success criterion.
onblur event to change the context.Editorial Note: There are many more scripting techniques to open a new window than are mentioned here.
Individuals who are unable to detect changes of context or may not realize that the context has changed are less likely to become disoriented while navigating a site. This applies to people in the following ways:
Individuals who are blind or have low vision may have difficulty knowing when a visual context change, such as a new window popping up, has occurred. In this case, warning users of context changes in advance minimizes confusion when the user discovers that the back button no longer behaves as expected.
Some individuals with low vision, with dyslexia and who have difficulty interpreting visual cues may benefit from additional cues in order to detect changes of context.
People with certain cognitive disabilities do not get confused if automatic redirects are performed by the web server instead of the browser.
Changes of context that are not initiated by a user action can be very irritating for people without disabilities.
Editorial Note: The first two benefits were simply copied from WCAG 2.0. The last one is a mainstream benefit that should not be added to the guidelines.