I recall there being a thread devoted to a rather simple opt-out option for pop unders. It's something that I ran on a previous computer, but that computer is now spare parts, and I'd love to run it on this one.
However, I can't seem to find said thread. I've done a Google search on The-W. I've perused the Internet & Computer forum here. I've even dug through CRZ's World, because I think he mentioned it after it had been around awhile.
I'm pretty sure the little curved arrow on the right is the "BACK" button, as in "Go back to the normal 'now playing' panel". EDIT: My bad. It's the "Play" looking button on the left you want. Hit that.