Placing doors on cliffsides [A7]

So, this morning, I saw that you could place doors in the “place furniture” menu, and doors can be placed on walls, as you would expect. But everything that can be placed on walls can also be placed on the side of a cliff, so:

Perhaps doors etc. should have to be placed at ground level, and on a wall unlike other things like flower pots.

I actually like this even if it is a bug because in alpha 8 when we can do micro-mining(i think) we could make trap door and make mazes and in alpha 9 shoot through little murder holes