Wow, I didn't know i can use an expression when spawning an object! That's a great feature, the most useful one I've learned in months. Thank you for making such a great tutorial.
On the other hand, I think this method would lag a lot if i try to use it for making bigger tile maps.Wouldn't it be better if instead of destroying every tile every tick, and then recreating the whole map, you just change the tile that's under the mouse?
Here's my try for that:
dl.dropbox.com/u/52670878/MapArrayEditor.cap
It's an edit of an old example made by Thuwe, redesigned for superspeed when making huge maps.