Hi. HTML5 introduces inert subtrees [1] which are supposed to make a portion of the document inactive (not interactive for the user):
"When a node or one of its ancestors is inert, then the user agent must act as if the element was absent for the purposes of targeting user interaction events, may ignore the node for the purposes of text search user interfaces (commonly known as "find in page"), and may prevent the user from selecting text in that node." There are number of approaches discussed at w3c bugzilla [2]: 1. Map it to MSAA STATE_SYSTEM_UNAVAILABLE (aria-disabled analogue applied to any element. In this case inert subtree is recognized by existing screen readers as not interactive but it seems it's easy discoverable what is unwanted, for example, in case of modal dialog. Another possible disadvantage is disabled controls can't be differentiated from controls of inert subtree. 2. Map it to aria-hidden. aria-hidden implementation varies from browser to browser: Chrome removes it from accessible tree, Firefox exposes "hidden" object attribute. Having the same ambiguity in inert subtree implementation seems unfortunate. 3. Remove from accessible tree approach (Chrome aria-hidden impl) While it should work in most cases but it's not author error prone approach and it doesn't 100% go with inert subtree description since inert subtree may allow text selection (refer to "User agents should allow the user to override the restrictions on search and text selection, however."). Also screen magnifies or other AT might want to "see" inert subtree, having no accessible prevents them from this. 4. Expose "hidden" object attribute on root (or every item from subtree) of inert subtree (Firefox aria-hidden impl) AT decides what it wants to do with it: either completely ignore it or not. I'm not sure though if making the same mapping as aria-hidden is a good choice. 5. Invent something new. AT should support it and it takes a time but if nothing from existing things suites well for inert subtrees then perhaps no other alternatives. I'd love to hear your thoughts. Thank you. Alexander. [1] http://www.w3.org/html/wg/drafts/html/master/editing.html#inert-subtrees [2] https://www.w3.org/Bugs/Public/show_bug.cgi?id=23350 _______________________________________________ Accessibility-ia2 mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/accessibility-ia2
