Right-click on an open tab and choose "Bookmark All Tabs" or CTRL+Shift+D.

Edit: The following is incorrect; it is due to an add-on that I have installed. The option is still on the Menu Bar but not on the Firefox button menus. To temporarily display the Menu bar, press the ALT key or the F10 key and choose Bookmarks > Bookmark All Tabs from there.

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Right clicking on the tab does indeed give me the option to bookmark the tab set. Thanks for that.

On the other hand, the menu tab you mention is not shown on my installed copy of v 5.0.1

Here's what's listed under 'Bookmarks' on my Menu Bar:

Bookmark This Page Subscribe to This Page ... Show All Bookmarks

Bookmarks Toolbar

Recently Bookmarked Recent Tags

Get Bookmark Add-ons

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Did you try pressing the ALT key or F10 key to get the old Menu Bar (File, History, Edit, View, Bookmarks, Tools, Help all on one line) to temporarily display in the upper left? That is in the second paragraph of my post.

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Thanks for the follow-up. The ALT and F10 options weren't available since I keep the Menu Bar displayed all the time. I tried disabling the Menu Bar, then using ALT and F10, which caused the Menu Bar to be displayed, but the Menu Bar options under Bookmarks were the same as I had seen before. The Bookmark All Tabs option was not included in the list.

Sorry, it's due to an add-on that I have installed. I edited my prior post, striking over that part about the Menu Bar.

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I'd be interested in knowing about that add-on and its capabilities. Thanks for your help in resolving this and enabling my use of bookmarking tab sets. The right click option will work just fine for me.