Remove pointer-events from active and disabled things

1. Adding `pointer-events: none` for active thumb/dot makes two things: it fixes a very minor bug when clicking two pixels on the right of the thumbnail makes the thumbnails move a bit, and it makes the active dot not to have pointer cursor — as it's already chosen there is no point to have events on it (pun intended).

2. And adding `pointer-events: none` to the disabled arrow makes the cursor to propagate to the element below, right now there could be sometimes a default cursor over it instead of a grab one (and I think that `pointer-events` for disabled is a much more appropriate way instead of just cursor change).