Some of the calls in our codebase will call for the `.keys()` method a
lot, so this caches the results and returns them rather than mapping
the array if it knows the state to be the same as before.
If a user clicks on the pill container and not directly on a pill
or on an "x" inside of a pill, it should be presumed they are
trying to input new text. This effectively makes the whole non-pill
section an input bar.
Brock Whittaker