Messing with maps...

Now, I could be mistaken, it has been awhile... but I remeber seeing the check to remove the floating island in Bank EE.

EE/9AF1 is labeled as where it starts but I couldn't begin to say how it works.

The auction house does it (to display a closed chest and an open chest using event command 73-75.
Or, search for the line
"Replace current map's layer" in the event log.

Best I can help, hope it helps at all.