JAWS reads absolutely-positioned live regions when CSS transforms are applied to the region's parent

[mra11yx]

Summary

Example:

1. Open JAWS
2. Open the following CodePen in Firefox 62: https://codepen.io/mra11yx/pen/YObLrQ
3. Tab to each of the buttons and activate them

Expected result

JAWS should not read the contents of a live region when CSS transforms are applied to / removed from an ancestor of the live region

Actual result

If an ARIA live region is absolutely positioned (for instance, by setting it up as a screen reader-only region so that it can be used as a "global" bucket for screen reader messages), JAWS responds to the addition or removal of the CSS transform property on any parents of this div by reading the live region's content. This does not happen if the live region is not absolutely positioned.
While the above situation may appear to be a minor edge case, this behavior can easily occur in a production site - for example, if a transform is applied to the document body or HTML tag as a hack to make content display in a certain way. (I originally found the bug "in the wild.")

Example

https://codepen.io/mra11yx/pen/YObLrQ

Additional Information

JAWS version and build number

2018.1808.10

Operating System and version

Windows 7 and 10

Browser and version:

Firefox 62 (32-bit on Windows 7, 64-bit on Windows 10)

[JAWS-test]

• The problem persists (JAWS 2019, Firefox 68)
• It occurs not only when the CSS properties are changed at the parent element, but also at the element with the live region or a child element. And it applies to the change of several CSS properties: alert is not output (IE 11, JAWS) w3c/aria-practices#1138 (comment)
• The problem may be that the specification does not say exactly when a live region will be output: Alert Pattern and example: Reference live region guidance for explanation of changes that trigger live events w3c/aria-practices#1139

[ZoeBijl]

@JAWS-test note that the ARIA Authoring Practices is not a specification but a note. It can’t specify what a screen reader MUST do.

[JAWS-test]

@ZoeBijl That's right, I didn't exactly understand that back then. The output of alert is clearly regulated in the ARIA specification.

[lamador]

Issue was not reproducible in Windows 10 using the latest versions of JAWS 2020 (2020.2004.66) and Firefox (76.0.1 (64-bit)).