Love it! Thanks!
But, how to start a new tab group?! -> Just found an easy solution: just "import URLs" a new url with a description. See in "Export" on how to format it. Any imported url will be added to your list. Don't include all ;-)

Almost useless. Does not save "new tabs" and pages like "about:config". Reverses the order of tabs and does not allow to save tabs in file on disk.

WARNING: This extension does NOT save your windows with tabs. I was hoping to find an addon for firefox similar to Cluster Tab Manager on Chrome, so I thought this would be it.

NOPE. This only temporarily condenses your tabs and they will NOT BE SAVED for later. You could " star" a tab, fooling you into thinking it will be saved for later (like when you want to open up a new window and load them up there) but it WILL NOT. Not only that, but the buttons on the UI are very unintuitive. SO MANY BUTTONS just mass condense your tabs without asking which tabs you want to be saved. Some of these buttons will also even automatically delete the condensed tabs after a couple seconds without user input!

So many good porn tabs lost in an instant... Might as well just go back to using my already cluttered and filled bookmarks manager...

excellent extension, well recommended

This addon is great, but it would be even cooler with more keyboard shortcuts(like send link to specified group etc.).

I'd say this is a "must have" addon.

Not functional on Android even though there is no notice of incompatibility.