The `mousedown` event happens before the `focus` event. When we
`e.preventDefault()` in this listener, the `focus` event will not fire.

This also means that the focus is not lost on the actual `input`
component which in turn means that we can maintain the selection /
cursor position inside the `input`.

We still use the `refocusInput()` as a fallback in case something else
goes wrong.

Now that we use the `mousedown` event instead of the `click` event, we
have to make sure that we handle the `enter` and `space` keys
explicitly.

This used to be covered by the `click` event, but not for the `mousedown` event.

…oboxButton`

We go to the last one on `ArrownUp`, but we forgot to do this on
`ArrowDown`.

Not related to this PR, but noticed it and fixed it anyway.

While we are typing, the flag can remain true. But once we stop typing,
the `nextFrame` handler will kick in and set it to `false` again.

It currently behaves as a debounce-like function such that the
`nextFrame` callbacks are cancelled once a new event is fired.

This allows us to keep re-adding dispose functions and only register the
callbacks once.

Ideally we can use a `Set`, but we also want to remove a single callback
if the callback is disposed on its own instead of disposing the whole
group. For this we do require an `idx` which is not available in a
`Set` unless you are looping over all disposable functions.

Co-authored-by: Jonathan Reinink <jonathan@reinink.ca>

Co-authored-by: Jonathan Reinink <jonathan@reinink.ca>