[Bug] Layers being applied outside of floating dimension region when underwater

[Dannypan]

I made a custom floating dimension layer to be added underwater and that worked fine, the terrain is all correct.

However, the layers are being applied to the dimension's 128x128 tiles, not just the editable area. This is resulting in scenarios like this where the layer (in this case, coral) is only meant to be on a small shelf. Instead, it's...

I'm gonna guess this is because the floating dimension checks for air around the editable area and knows to not place layers there, but doesn't do this check for water.

Either way, it would be brilliant if this could be changed. The floating dimension has a serious amount of potential for creations like this,
a lot more than just adding floating islands.