Not sure why this would change, but here is a thing to check:

In the address bar, type about:config and Enter In the search here, type mousewheel.default.action, or as much of it as necessary for you to find it. Make sure mousewheel.default.action is set to 1

I can't get mousewheel to scroll tabs if i tried, and it is not related to the setting above (scrolling through a tabs history, if any, is). But if the setting isn't 1, the page will not scroll.

Have you clicked in the content area before attempting to scroll the page? maybe the tabs are keeping/stealing focus somehow.

Edit: Do you have a gaming mouse or macro-enabled mouse or hub?

Does it help if you click elsewhere in the user interface or in the web page area in case currently the Tab bar has focus ?

Try the Firefox version from the official Mozilla server if you currently use a version from the repositories of your Linux distribution.

• https://www.mozilla.org/en-US/firefox/all/

Thanks both,

Mousewheel.default.action was already set to 1.

But now the problem seems to have gone away - scrolling moves up and down in the current tab as I would expect, even when I don't click in the content area after selecting the tab.

It's an ordinary Microsoft optical USB mouse, though plugged into a KVM switch.

I've had this problem before, so I'll leave this thread open for a little while and see if it comes back. If it does, I'll test it plugged directly into the computer.

I can't remember where I installed FF from, but if necessary I'll download from the Mozilla server.

Thanks again for your help.