[Notes]: - The issue is also reproducible if the Developer Tools are in a separate window. - This issue is not reproducible for other tools. For example when the Inspector tab is focused and the Developer Tools are horizontally resized to the right side, the right column is moved to under the left column. [Affected versions]: - Nightly 60.0a1 (2018-03-01) try build [Affected Platforms]: - All Windows - All Mac - All Linux [Prerequisites]: - Have the latest try build 60.0a1 from (2018-03-01) installed. - The "Accessibility" option is checked in "Toolbar Options". - Have the Developer Tools are docked to the right side of the browser. [Steps to reproduce]: 1. Open the Nightly try build with the profile from prerequisites. 2. Navigate to any website press the "F12" key and enable Accessibility features. 3. Horizontally resize the Developer Tools to the right side. 4. Observe the "Accessibility" panels. [Expected Results]: - The right panel is moved under the left one. [Actual results]: - The panels are not rearranged. [Additional Notes]: - Attached a screen recording with the issue.

It seems that the issue is also reproducible if the browser is resized to the mobile view and the Developer Tools are docked to the bottom side of the browser. Attached a screen recording for this behavior.

Will be fixed in the next try.

I have retested this issue on the latest Nightly try build (2018-03-12) and the issue is no longer reproducible. Tested on Windows 7 x64, Mac Os 10.12 and Arch Linux.

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.