Thanks! i had already looked at that and didn't think was any of those.
I just now posted at Tree Style Tabs author's (Piro) forum at github. I was very lucky...he was online. I posted, went to the bathroom, came back and had a reply from him.
Upgrading messed up a bunch of my settings but at first everything seemed fine. Chachaz asked me how my upgrade experience was and I posted it was fine....but that was right after I upgraded. Now, a week later, I am seeing a lot of problems showing up.
It was this setting in about:config that upgrading changed to "true" that I had set to "false" in Fx 10. Note in my screenshot that Fx claims "true" was USER setting. NO WAY would I set it to show all tabs previews! Piro said to set it to "false". I did and now I have the text list of all tabs back. I didn't even have to restart Fx.