Before doing anything else please update to Firefox 23.0.1 Update Firefox to the latest release. Firefox 19 is no longer supported, and has several major security issues and stability/performance bugs.

You can look at the toolkit.scrollbox.* prefs

• toolkit.scrollbox.smoothScroll = false (requires a restart)

Note that you can double-click or triple-click the scroll buttons.

I do not want to upgrade.

Is anyone willing to help me answer the question I asked for the version I want to use?

Did you try the pref(s) that I posted above?

browser.tabs.animate is for when you delete a tab (Bug 380960).

I hadn't seen your response, owing to the huge amount of vertical blank space in this forum software coupled with the large blank distance between the forum content and the scroll bar off to the side.

I have tried it now. It seems to be doing what I want. I think a person making this change might want to fiddle with toolkit.scrollbox.clickToScroll.scrollDelay

Triple click is hard to click for me but good to know about.

Double click seems to move it a fair amount but not by one tab bar's worth. What amount is it the double click is scrolling the tabs by?

I have the layout.css.devPixelsPerPx set non-default, for what that's worth to know.

Thanks for your response.

Is there a specific reason you don't want to upgrade? Using such an old version leaves you vulnerable to security holes and performance issues, so i'd like to help you update if possible.

It's been years since I've like any changes made to the UI. The latest big change I know of is the Download window, made in at way I don't like. That change alone is sufficient to keep me from wanting to upgrade. Every time you upgrade much there's a chance an add-on that you like is not compatible. Every time you upgrade there is a likelihood of having to spend hours searching for preferences to change in about:config to restore the old behavior that you liked better than the new behavior.

There's not a change in the UI I've like since version 3.5 or so. I'd be perfectly happy to be able to pick an old version and never have the UI upgraded at all. Security updates should be as separated from UI changes as physically possible.

I have no more need or desire for changes in browser UIs than I have for my car to switch the location of the ignition key , glove box, and AC controls around.