Affected versions

• 78.0a1 (07-04-2020)
• 77.0b2
• 76.0

Affected platforms

• Ubuntu 18.04x64

Steps to reproduce

1. Launch Firefox.
2. Make sure this window is maximized and go to reddit.com or youtube.com
3. Open a new window and then minimize it.
4. From maximized window Quit via the Hamburger menu.
5. Reopen Firefox with the same profile.
6. Restore the previous session.

Expected result

• Both windows are correctly restored.

Actual result

• The maximized window is corrupted, the page is displayed on the left up side and is at the same dimension like the minimized window.

Regression range

• This is not a recent regression since I was able to reproduce it on 67.0. I’ll come with a regression range asap.

Additional notes

• See the attached screen recording with the issue.
• On about: pages and wikipedia.org the issue isn’t reproducible
• This is similar to the 1505027
• By quitting Firefox via the Hamburger menu from the minimized window, both windows are correctly restored.