Hi Tor Nordam,

Thanks for reporting this — middle-click should definitely open links in a new tab if browser.tabs.opentabfor.middleclick is set to true.

Here are a few things to try:

• Check for system-level overrides: On Xubuntu (XFCE), middle-click may be mapped

to paste by default. You can check your mouse/trackpad settings in Settings > Mouse and Touchpad to confirm.

• Test in Safe Mode: Launch Firefox in Troubleshoot Mode (Help > Troubleshoot Mode)

to rule out interference from extensions or custom settings. Try using another mouse or touchpad gesture, in case it's hardware-specific or being intercepted.

• Check about:config for these preferences:

middlemouse.contentLoadURL → set to false middlemouse.openNewWindow → set to true middlemouse.paste → set to false

If the issue persists even in Safe Mode and with correct settings, it could be a regression specific to Firefox 135 on certain Linux configs. Let me know, and we can escalate or file a bug report together.

— Nathan

What Desktop? X11 or Wayland? What happens on this site? https://www.onlinemictest.com/mouse-test/

Try downloading Firefox from Mozilla, run firefox-bin from the folder and see if you have the same issue. https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

I tried the mouse test website, and it didn't recognize middle click. Then I plugged in another mouse, and middle click then opened new tabs as expected. So the problem is definitely not with firefox, and we can close the issue.

It's strange, though, I've been using this mouse for years, and now it suddenly stopped working after I did a fresh install of linux.