I wanted a button to swap the hotbar with the last inventory row, in order to toggle between two bars with different tools, or an exploration bar and a combat bar.
There are several existing mods that can do this, but some are complicated and do other things too, aren't available for the version/modloader combo I needed, require mouse scrolling, or otherwise didn't quite fit the bill.
So here's a simple mod that does one thing. It defaults to the backtick (`) key but can be rebound.

