Affected versions

• 67.0.2, 68.0b7, 69.0a1 (2019-06-03)

Affected platforms

• Windows 10, macOS 10.11, Ubuntu 18.04;

Steps to reproduce

1. Launch Firefox, access any webpage;
2. Enable DevTools and enable RDM;
3. Grab the view-port and resize it so it expands past the available area;
4. Release the mouse cursor;
5. Grab the resize icon and resize to the initial width.

Expected result

• The resize action follows the mouse;

Actual result

• The resize action appears to be triggered with a delay, the mouse cursor jumping and not remaining in the same position as the resize icon;

Regression range

• does not appear to be a regression, reproducing the issue with 45.3.0esr and other older versions as well;

Additional notes

• attached recording with the issue;

Thanks for finding and posting this.