rockofox

Another reproducible way to trigger this I found is by hovering over an application in the dock and using Command-Tab to switch to an application on an adjacent display.

Hmm, I tried reproducing this both on NixOS + Firefox 122 and macOS + Firefox 123/Dev, but I didn't run into the issue. What theme are you using in Firefox?...

Hmm, weird, I tried it out on i3 default configuration with no desktop environment and still can't see any border

Sorry for the late reply, I was busy with other things at work. Yes that works, thanks for your help 😄

Hmm, I can't reproduce it on my setup. Could you tell me what OS and what Firefox Edition (Standard/Developer/Nightly) you're running? Maybe I can find a way to reproduce it