A few days ago, I accidentally closed 1 window (clicked the "X" in the upper-right corner) that had 248 tabs in it, without realizing it. Since then, I've 'properly' closed Firefox (Menu icon; Exit) and reopened it again many times. I have 3 other windows open in my current session, each with many-hundreds of tabs in them (one has 1335 tabs!). Fortunately, I have an archived copy of my entire Profiles folder from a month ago. Saving aside my current sessionstore.jsonlz4 file, and substituting the month-old one into its place, then restarting Firefox, shows me that I still have that old 'lost' window there (with all 248 tabs intact), along with the other (old) 3 windows. But I've made a lot of changes to the tabs in those other 3 windows since I 'lost' the 4th one; so I can't just use that backup of all 4 windows, going forward now. I need to recover that 4th window, into my current session. Is there some way to make a copy of one entire window (with all its contained tabs with their titles and URLs) from one session, close Firefox, then open a new Firefox session and 'paste' those contents into a new (empty) window? I downloaded the "Copy All Tab Urls" Add-on (by Michele Pezza), which allows me to copy that one window's 248 'lost' tabs (titles and URLs) to my clipboard. Which is fine for pasting that list into a Word document. But I can't figure out how to 'paste' that list into a new Firefox window, as properly-configured individual tabs. Or, maybe there's some other solution? I can't be the only one who's accidentally closed a big fat window inside a multi-window session, and gone too far from the event to simply restore the whole session from a backup. Any help would be hugely appreciated. Thanks in advance!