I discovered this by accident.
If you have multiple tabs open in Firefox, hit the F12 key and you will see a “Showcase” view that shows you large thumbnails of all the open windows…
It appears to be this plug-in: https://addons.mozilla.org/en-US/firefox/addon/1810
I don’t -think- I installed this on my own.
To quote former A.G. Gonzales “I have no recollection of those events”.
So I think this is a handy utility Zonbu included in the default build, cool. Can someone else confirm that they have this F12 functionality?
Kind of neat. I like it.
-Mr. Zonbu
Real life with the Zonbu Mini-PC 
Yup – works for me too (and I too have no recollection of installing it). There’s also a ‘personal content filter’ in the add-ons that I didn’t install …nor can i find anything about it on the add-ons site.
Yes, it’s enabled by default. We thought that it was a cool add-on. There is also a content filter by default too. It’s disabled. You can customize it in Tools->Content Filter Preferences.