Addtiledef
 

Perhaps a little trivial, but I think whenever there's an addtiledef and no image is located(not downloaded yet), it should turn the tileset all black, replacing the pics1 temporarily. This is strictly from a 'professional' standpoint.
If I pay for a game and the first thing I see when I go to get on a server like Zone is a bunch of garbled tiles, it's a little turn off. I mean it doesn't break the game, but I think it could help the appearance a bit.

Seconded.

Motion carries.