Firefox without window decorations after update

Question

I'm using Firefox on Devuan Chimaera with Fluxbox as my window manager.

After the latest Firefox update (to version 91.5.0esr) the browser is started without window decorations. This seems to make it stuck to the top left of the desktop. The browser window also is always in front of other applications.

How do I fix this?

Answer 1

According to bug 1714353 in the Mozilla bug tracker the issue seems to be ultimately caused by incorrect color depth handling in Fluxbox (see discussion here). The root cause apparently has been fixed upstream, but the patch doesn't seem to have made it into the Debian Fluxbox package yet.

If you don't want to recompile your window manager you can try mitigating the issue on the Firefox side. In about:config set these two options:

• gfx.webrender.all → false
• gfx.webrender.force-disabled → true

Alternatively add the following two lines to prefs.js or user.js in your Firefox profile:

user_pref("gfx.webrender.all", false);
user_pref("gfx.webrender.force-disable", true);

Then restart Firefox. That resolved the problem for me.