196349 2019-03-28 06:13:19 -0700 AX: ARIA live regions stop notifying of changes after having a certain number of child elements 2019-03-28 06:33:12 -0700 1 1 1 Unclassified WebKit Accessibility Safari 12 Mac macOS 10.14 NEW InRadar P2 Normal --- 1 pilky webkit-unassigned webkit-bug-importer oldest_to_newest 1522046 0 366168 pilky 2019-03-28 06:13:19 -0700 Created attachment 366168 HTML page to reliable reproduce ARIA live region bug with VoiceOver Summary: I have been attempting to use ARIA live regions to try and notify users of accessibility tools of changes to a list (acting as a chat message thread). Unfortunately, it seems that the notification of changes stops after the region contains a certain number of child elements. In the case of a <ul> element, notifications stop after I add 16 <li> elements. If I change to a <div> element with <p> child elements it stops notifying after there are 24 <p> elements. I have been unable to find any information in any specs or documentation around ARIA that specifies any upper limit. I have tested this in both Safari 12.1 (14607.1.40.1.4) and the latest Safari Tech Preview (Release 78, WebKit 14608.1.9.1). I have also discovered the same issue in Chrome (73.0.3683.86). This make me think this is most likely either a WebKit bug or a VoiceOver bug (I'll also be filing a bug with Apple in case it is the latter). This is all on macOS 10.14.4 Reproducing: I have attached a small HTML page that allows you to test both the above cases: 1. Open the arialivebug.html file in a WebKit-based browser on macOS 2. Enable VoiceOver (usually Command-F5) 3. Click the Start button below the List Test heading (you can change the value but 20 is a good number to show the bug) 4. Listen to VoiceOver notify the user of changes 5. After the List Test has finished, click the Start button for the Paragraph Test 6. Listen to VoiceOver notify the user of changes Expected Result: VoiceOver notifies the user of all changes to the live regions Actual Result: VoiceOver stops notifying the user of changes after 16 child elements in the list and 24 child elements in the div Workaround: From my testing it seems you can work around this by creating a new live region once the previous one is "full". Of course this has the downside of making the HTML less semantic (which can harm accessibility in other ways), but does ensure users will always be notified. 1522050 1 webkit-bug-importer 2019-03-28 06:33:12 -0700 <rdar://problem/49377535> 366168 2019-03-28 06:13:19 -0700 2019-03-28 06:13:19 -0700 HTML page to reliable reproduce ARIA live region bug with VoiceOver arialivebug.html text/html 1539 pilky PGh0bWw+CjxoZWFkPgoJPHN0eWxlIHR5cGU9InRleHQvY3NzIj4KCQlib2R5IHsKCQkJZGlzcGxh eTpmbGV4OwoJCX0KCQlzZWN0aW9uIHsKCQkJbWFyZ2luOiA1cHggMTBweDsKCQl9Cgk8L3N0eWxl PgoJPHNjcmlwdD4KCgkJZnVuY3Rpb24gcGVyZm9ybUNvdW50KGlucHV0SUQsIGNvbnRhaW5lcklE LCB0YWdUeXBlKSB7CgkJCXZhciBpbnB1dFZhbHVlID0gZG9jdW1lbnQuZ2V0RWxlbWVudEJ5SWQo aW5wdXRJRCkudmFsdWU7CgkJCXZhciBjb250YWluZXIgPSBkb2N1bWVudC5nZXRFbGVtZW50QnlJ ZChjb250YWluZXJJRCk7CgkJCXdoaWxlIChjb250YWluZXIuZmlyc3RDaGlsZCkgewoJCQkJY29u dGFpbmVyLnJlbW92ZUNoaWxkKGNvbnRhaW5lci5maXJzdENoaWxkKTsKCQkJfQoJCQl0aGlzLmFk ZE51bWJlcigxLCBpbnB1dFZhbHVlLCBjb250YWluZXIsIHRhZ1R5cGUpOwoJCX0KCgkJZnVuY3Rp b24gYWRkTnVtYmVyKG51bWJlciwgbWF4TnVtYmVyLCBjb250YWluZXIsIHRhZ1R5cGUpIHsKCQkJ aWYgKG51bWJlciA+IG1heE51bWJlcikgewoJCQkJcmV0dXJuOwoJCQl9CgkJCXZhciBlbGVtZW50 ID0gZG9jdW1lbnQuY3JlYXRlRWxlbWVudCh0YWdUeXBlKTsKCQkJdmFyIHRleHQgPSBkb2N1bWVu dC5jcmVhdGVUZXh0Tm9kZShudW1iZXIpOwoJCQllbGVtZW50LmFwcGVuZENoaWxkKHRleHQpOwoJ CQljb250YWluZXIuYXBwZW5kQ2hpbGQoZWxlbWVudCk7CgoJCQlzZXRUaW1lb3V0KGZ1bmN0aW9u KCkgewoJCQkJdGhpcy5hZGROdW1iZXIobnVtYmVyICsgMSwgbWF4TnVtYmVyLCBjb250YWluZXIs IHRhZ1R5cGUpOwoJCQl9LCAxMDAwKTsKCQl9Cgk8L3NjcmlwdD4KPC9oZWFkPgo8Ym9keT4KCTxz ZWN0aW9uPgoJCTxoMT5MaXN0IHRlc3Q8L2gxPgoJCTxwPkxpc3RzIG5vdGlmeSB1bnRpbCBhIG1h eCBvZiAxNiBjaGlsZHJlbjwvcD4KCQk8bGFiZWw+TnVtYmVyIHRvIGNvdW50IHRvOjxpbnB1dCB0 eXBlPSJ0ZXh0IiBpZD0ibGlzdC1jb3VudCIgdmFsdWU9IjIwIj48L2xhYmVsPiA8YnV0dG9uIG9u Q2xpY2s9InBlcmZvcm1Db3VudCgnbGlzdC1jb3VudCcsICdsaXN0LXRlc3QnLCAnTEknKSI+U3Rh cnQ8L2J1dHRvbj4KCQk8dWwgaWQ9Imxpc3QtdGVzdCIgYXJpYS1yb2xlPSJsb2ciIGFyaWEtbGl2 ZT0iYXNzZXJ0aXZlIj4KCQk8L3VsPgoJPC9zZWN0aW9uPgoKCTxzZWN0aW9uPgoJCTxoMT5QYXJh Z3JhcGggdGVzdDwvaDE+CgkJPHA+RGl2cyBub3RpZnkgdW50aWwgYSBtYXggb2YgMjQgY2hpbGRy ZW48L3A+CgkJPGxhYmVsPk51bWJlciB0byBjb3VudCB0bzo8aW5wdXQgdHlwZT0idGV4dCIgaWQ9 InBhcmFncmFwaC1jb3VudCIgdmFsdWU9IjMwIj48L2xhYmVsPiA8YnV0dG9uIG9uQ2xpY2s9InBl cmZvcm1Db3VudCgncGFyYWdyYXBoLWNvdW50JywgJ3BhcmFncmFwaC10ZXN0JywgJ1AnKSI+U3Rh cnQ8L2J1dHRvbj4KCQk8ZGl2IGlkPSJwYXJhZ3JhcGgtdGVzdCIgYXJpYS1yb2xlPSJsb2ciIGFy aWEtbGl2ZT0iYXNzZXJ0aXZlIj4KCQk8L2Rpdj4KCTwvc2VjdGlvbj4KPC9ib2R5Pgo8L2h0bWw+