HTML5 clarifying non-interactive user agents

Hi! The following has been added to the wiki at http://www.w3.org/WAI/UA/work/wiki/HTML5_review_by_UAWG_notes#Non-Interactive_User_Agents:


    Non-Interactive User Agents

The current draft HTML5 spec says:

    <blockquote>*
    *

    *Non-interactive presentation user agents*

    User agents that process HTML and XHTML documents purely to render non-interactive versions of them must comply to the same conformance criteria as Web browsers, except that they are exempt from requirements regarding user interaction.

    Typical examples of non-interactive presentation user agents are printers (static UAs) and overhead displays (dynamic UAs). It is expected that most static non-interactive presentation user agents will also opt to lack scripting support.

    A non-interactive but dynamic presentation UA would still execute scripts, allowing forms to be dynamically submitted, and so forth. However, since the concept of "focus" is irrelevant when the user cannot interact with the document, the UA would not need to support any of the focus-related DOM APIs.

    </blockquote>

It is very important that developers should not relegate user agents to the "non-interactive" category if there is benefit to the user in being able to interact with them.

*Use case:* Imelda uses a screen enlarger. She runs an application that displays a static, web-based slide detailing today's weather forecast. Imelda uses a screen enlarger, and normally reads blocks of text by having the magnifier track the text caret as she moves it through the content. However, as the developers considered theirs a non-interactive user agent, they left out the ability to do caret browsing. With luck, the screen enlarger will be able to access the application's DOM and determine the screen coordinates of each word, but it would certainly be easier if the application supported caret browsing.

*Use case:* The weather application that Imelda is running allows the user to select text with the mouse and automatically copies that text to the clipboard. However, the developers did not consider this "focus" or "activation", or even "selection" because the selection does not persist and the user can't perform their choice of actions on it. However, by this decision they are making functionality available to only one input modality, and users who rely on other modalities such as keyboard or speech recognition are denied full access. In this case, the developers should not have considered their application non-interactive, and instead implemented full focus and selection functionality.

*Recommendation:* The HTML5 spec should include wording that clarifies that user agents should not consider themselves non-interactive if they render content to the user on any system that can take input, and more specifically should not omit support for focus-related DOM APIs just because they do not expect to be taking input. Ideally it would include use cases similar to the above in order to help readers understand the issue.