Understanding SC 2.4.11: Focus Not Obscured (Minimum) (Level AA)

Non-persistent opened information

A number of components on the web open (or disclose) additional content (on activation or on focus) intended for immediate user interaction or information. This new content is often on top of other content, obscuring it. Examples of such components are menu items, select element items, combobox lists (and other dropdown items), date picker calendars, and tooltips. The common trait of all these components is that they are not expected to persist after being acted on or once they are no longer the primary point of user interaction. Such non-persistent disclosures do not fail this SC since they do not obscure the item with focus. However, if an author allows such components to persist after the user has 1) activated one of the opened items or 2) moved the focus away from the triggering item and the additional content, it is at risk of failing this criterion by obscuring the item with focus.

User openable, persistent disclosures

Some disclosure patterns provide a mechanism for the user to open additional content that remains open until intentionally closed by the user. Accordions are a simple example of such a pattern. Chatbots and expandable side navigation are more complex examples. All of these patterns can be implemented so they are not at risk of failing this SC. Some possible approaches are:

• When the additional content appears, it displaces existing content. An accordion is an example of this. When an accordion is opened, the disclosed content shifts existing content further down the page. Since the new content does not obscure existing content, it cannot obscure the item with focus.
• When the additional content appears, existing content reflows. The popout sidebar on the WCAG standard is an example of this pattern. When the side menu is activated, it opens a new section of information along the left side of the page. The main content area is reduced horizontally to accommodate the new content, and the existing content reflows to fit in the thinner space. As a result, there is no overlapping content between the two sections; the item receiving focus, whether in the left navigation or in the main content, will not be obscured by the other section.
• When the additional content is opened, it takes focus and the tab ring is constrained to the new content until it is dismissed. This modality is somewhat like a dialog, in that a user cannot navigate beyond the opened content by keyboard without dismissing it first (typically by pressing Esc). However, unlike in a modal dialog, in some implementations a pointer user may be able to interact with content outside the opened section without dismissing it. Since this pattern potentially creates an inequitable experience between keyboard and pointer users, it should be used cautiously. That said, it does prevent the opened content from obscuring the keyboard focus in the main content, and thus should pass this SC. This is described and demonstrated in a short video in the Knowbility article in the reference section, under the section heading Keep keyboard focus in the slide-out navigation until it's closed.
• The disclosure expands into an area of the page containing no other content. Many pages are designed with wide margins, providing significant white space into which new content can be opened. Many chatbots and toast notifications are designed to 'slide up' into the right unpopulated side of a page. Where authors are careful to ensure content is not obscured at each breakpoint in a responsive design, no obscuring of other operable content need occur.
• When focus leaves the additional content, the additional content is automatically hidden or collapsed, or the content can be hidden or collapsed by use of a dedicated keyboard command (for example, the Escape key.) This is very similar to patterns discussed previously under Non-persistent opened information. A distinguishing factor can be that the user's last point of interaction in the disclosure is preserved (it persists) even though it may be hidden until a user returns. Some trees and side navigation patterns behave this way.

In recognition of more complex interfaces and user needs there is a note: Content opened by the user may obscure the component receiving focus. If the user can bring the item with focus into view using a method without having to navigate back to the user-opened content to dismiss it, this criterion would be passed. For example, keyboard actions that may allow the item with focus to be revealed include:

• using the Escape key to dismiss the obscuring content;
• using keys to scroll the content in the viewport to reveal the item with focus;
• issuing a key to move between overlays.

For example:

• A user opens a chat interface, which is a popover non-modal dialog. This results in some content of the underlying page being fully obscured. The user navigates away from the chat interface by use of the tab key, focusing onto a link that has been fully obscured by the dialog. The user presses the Escape key to close the chat interface, which un-obscures the link.
• A user expands a fixed-position page feedback component at the bottom of a Web page. They then use their keyboard to navigate to a link that's fully obscured by the expanded component and press the down arrow or space key on their keyboard to scroll the content on the page, un-obscuring the link.
• A user opens a web-based multi-user authoring application. An overlay appears displaying a list of people who have contributed to the document. The user tabs through the list of contributors and activates one of them. The application displays a new overlay, which obscures the first one, that displays that person's recent contributions. The user presses the F6 key to toggle the stacking order of the two overlays.