The idea there is what we call 'demo-mode', a new feature to try to enable helpful chatty features but for only _n_ page loads. So the full theme toggle (or Control Strip in Mac terms) is exposed on the first page load, but then is left collapsed into the gear on subsequent page loads to reduce clutter.

I don't think it should 'try to slide up then it dies'; do you mean you can't see the gear at all?