Adding/swapping a block bug

[mb324-unikent]

If you select a block to add/swap and then change your mind, you're told you're not allowed more than one block. You have to deselect the selected block and then select a different block. This isn't what you'd expect to have to do.

Note that this applies to where the definition says you can only have a single block.

You should just be able to select any block by clicking on it. Clicking on it should deselect any other selected block.