Pressed Alt+Tab and held Alt, mousewheeled over tabbox, it switched windows.

It does not wrap around when I reach the beginnign or end - should it?

It doesn't scroll the list like a regular scrollbar would but switches to the next/previous window on each wheel tick (which I think is what the user would expect), scrolling when the window would be out of view.

Bug 369661 is about the compact switcher, not the default one. So perhaps kwin itself needs to have some magic for that? Dunno. Still neat feature to have in the default layout I guess.