[Affected versions]: - Nightly 60.0a1 [Affected Platforms]: - All Windows - All Linux - All Mac [Prerequisites]: - Have the latest try build 60.0a1 from (2018-02-15) installed. - Accessibility tab is activated, but not enabled. [Steps to reproduce]: 1. Click the Accessibility tab from the tab strip. 2. Click the "Enable Accessibility Features" button. 3. Click the "Responsive Design Mode" button. 4. Click the arrow on the left side of the "document:" item and observe what happens next. [Expected result]: - The arrow points down and the line is expanded. [Actual result]: - The arrow points down but the line is not expanded. [Notes]: - The accessible picker is also broken and doesn't focus the specific line for the correspondent object from the page. - This is also reproducible when disabling the RDM and trying to use Accessibility on the normal mode page. - Attached a screen recording of the issue.

will be fixed in the latest try.

This issue is still reproducible on the latest try build (2018-02-23). Must note that the issue is intermittent and affects only certain websites, such as: - www.youtube.com - www.wikipedia.org - www.amazon.com - www.flicker.com - www.twitch.com - www.ebay.com - www.instagram.com - www.vk.com

will be fixed with latest try.

On the latest Firefox Nightly (Build ID: 20180426220144) the issue cannot be reproduced on Mac OS X 10.12, Windows 10 x64 and Ubuntu 16.04 x64, thus I will close the issue as VERIFIED FIXED.