Hopefully you keep some kind of session backups; that would be a lot to lose.!

I think the order of windows starts off as the order in which they are opened. I actually don't know whether Firefox can change the order without closing and re-opening windows. Have you discovered other applications that can do it?

Also, how would you alphabetize -- by the title of the page in the active tab?

Perhaps it would be useful to use a window/tab manager add-on, although any list of 150 items (and multiple sub-items) probably will require scrolling. I looked at Tabby --

https://addons.mozilla.org/firefox/addon/tabby-window-tab-manager/

-- and I can right-click a window in its list to name it, but I don't see a way to expand/collapse the list to window names for faster skimming. It does have pretty fast tab title search, if that would be helpful to you to find and switch to a tab of interest in the window you want.

Maybe there's something else out there that's better suited to your needs.

Hi, thanks for your reply! Yes, I keep session backups, as I've had the occasion to crash Firefox. Been there, done that! I'm trying to figure out what controls the order of window tabs in the win 10 taskbar - whether windows or Firefox.

I always have a tab in a research window that I've just searched on the subject, eg. "covid-masks" or "teaching-lesson plans" or "web hosting-security", etc. I keep that tab as the current tab when I switch to another window, therefore I can always see the subject of that window series in the task bar. The problem is that with 150 windows, it takes a while sometimes to find the specific window I need to get back to! If it were alphabetized, it would be far faster to find the window.

I looked at Firefox "tab managers", but they appear to only sort tabs within a window; not all the windows in the taskbar. I might have 3-4000 tabs open at a time, and this is way too many to have floating around without some sort of categorization!

I don't think Firefox or a Firefox add-on can sort windows on the Taskbar. The use of an extension like Tabby would be to more quickly find a specific tab (or window) from within Firefox while you are in some other Firefox window and switch to it directly without using the Taskbar.

Thanks for your reply! I tried Tabby, and while it is better than nothing if I truly have "lost" a window and just cant' see it with my scanning eye; it is still far more time consuming than just looking at the taskbar and finding the window that already has a key word. If I could find a way to sort the taskbar alphabetically, it would be by far the fastest method. Agreed though, if a person is trying to "remember" and find where a particular tab is - especially with hundreds, or in my case thousands of open tabs - then Tabby would be a God-send! Thanks for your suggestion.