HTML for all questions is attached to the document at all times.

It used to be that only the current question's HTML was attached to the page, and ko.applyBindings re-applied the bindings each time the question changed.
KO really doesn't like you doing this. There's a bug (or a feature?) with foreach where a foreach on n items would get applied n^2 times.

Now, all question HTML is attached to the document at init, and the visible: binding is used to show/hide them.
Fun fact: you can't have `visible: x, with: y` bindings on a single element. They interact with each other somehow, leading to all non-knockout event bindings getting lost.