Firefox window always starting maximized

Question

Intermittently Firefox reverts to opening its windows maximized. I expect it to remember last size and revert to that.

Ubuntu 18.04, latest patches, Firefox as supplied with Ubuntu, default GNOME desktop. When I was 17.04/Unity desktop (if that matters) it did re-open at same (non-maximized) size as last time I closed it. Now it sometimes does that, and that continues to work for a while, but sometimes reverts to always opening maximized, which I don't want.

As of today, for example, no matter what I do in the way of closing it, it re-opens maximized. I tried created a new temporary profile, but that didn't seem to change behaviour. I have done nothing "special" that I am aware of since it last worked, and I cannot figure how to get desired behaviour back.

• Does anyone else suffer this intermittent behaviour?
• Does anyone know what I can do to sort this out?
• If it is saving this setting somewhere in the profile (~/.mozilla/firefox/xyz.default/), which exact file is it in?

Answer 1

Well blow me down with a feather! To answer my own question, and help others, I have just come across https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1730410, including :

Almost all applications (Firefox, Nautilus, Google Chrome, PyCharm, Skype, Calendar and other) opens in maximized size if it window size was larger than some value (more than about 80% of display width and height) when application was closed.

and

This is indeed a mutter "feature". Use 'gsettings set org.gnome.mutter auto-maximize false' to turn it off.

No wonder it seems intermittent: if I close my window when it's 79% size it restores but if it's 81% it maximizes! Who dreams up such unintuitive behaviour?!

I confirm that making the FF window smaller before closing solves the issue. For my part I have run the suggested gsettings command to change the GNOME setting and now I can close from any size and it restores to that size as desired.