Okay, I figured a bit of firefix properties. Took a long time going through all that data, and I think it working now. Though, does that solve the accidentally clicking one of the tab on the left issue? I'll give it a shot. Anyway, thanks for testing and making sure JJ + J, you must have been profounded a lot while testing it. I apologize for that.
I didn't know you could use (ctrl + z) either, very helpful. Just configured firefox, and Voilà, ctrl + z works again.