EDIT: I'm guessing most of this is solved based on id:2604788

Descriptive Problem Summary:
Not sure if this is entirely a bug, but it is bothersome. I filled an iso map with 'grass' tiles, just a plain green diamond. I then placed other tiles over them, assuming the grass tiles would be destroyed since the new tiles covered the old ones. They aren't, I suppose since there are transparent parts to both icons. While I don't really like this, that isn't really the bug. When I run the game and walk around, the grass tiles underneath the other tiles flicker into view when I walk into them, and then disappear.

Numbered Steps to Reproduce Problem:
Run the program and walk around, crossing into non grass tiles.

Code Snippet (if applicable) to Reproduce Problem:
http://files.byondhome.com/Flick/isobug_src.zip

Expected Results:
Either the bottom turf should be deleted as there are no opaque pixels visible when covered with the new tile, or the bottom turf should not flicker into view when being entered.

Actual Results:
Bottom tile still exists as an underlay I assume, and flickers into view when entered.



Workarounds:
Go through by hand and delete all the grass tiles beneath the other tiles, or just dont fill an area and try to cover it up...