Hey @dakes - I know others have mentioned a similar approach, but I'll mark your post as a functional workaround until we have something more official in place.
The decision to not trigger onClick event handlers when clicking on whitespace is an intentional - but fairly contentious - one that is fittingly centered around the Button column type. Prior to this change, clicking outside the contained button but within the bounds of the cell itself would still trigger the onClick event, which was undesirable.
On a completely separate note, the new app builder that we recently released into public beta unlocks almost limitless customization and makes small tweaks like this trivial. I'd be interested in getting your thoughts, if you want to give it a try!