Tab Session Manager was my session manager of choice until I realized that it was at fault for a very annoying problem I was having.

I still use Windows 10 on my main computer and I run many multiple desktops. Sometimes up to twelve.

With TSM active, every time I restarted Firefox, all of its (many, many) windows—which had been distributed across multiple desktops—would open on a single desktop, leaving me with several minutes of work to reorganize them into something coherent.

As well, browser windows that I'd long since closed were also opening, adding to the clutter.

Eventually this became too annoying and I started probing into the cause. Disabling TSM immediately made the issue go away so I left it disabled and started using Tab Stash, which I don't like as much but when I restart FF all the windows stay where I had them.

I'd go back to TSM in a second if I knew the multiple desktop issue had been sorted.