The visual bug I was referring to:
note the fleet at STP(sc) before and after preview mode
gameID=155311Spring 09
http://puu.sh/g0xZN/f5e7b0e6a6.jpg (preview mode off)
http://puu.sh/g0y0D/1a48c86383.jpg (preview mode on)
For the F STP(sc), even though it was disbanded, and the Spring map shows it was disbanded last winter, it shows up on the Spring Moves Preview map. Very rare, non-harmful instance, but since I discovered it it's somewhat on my mind as an immediate observation about how handling coasts in adjudicators/programs is non-trivial.
There's a special .txt just for discussing how phpDip handles coasts (http://webdiplomacy.net/doc/coasts.txt) and they appear in the Gotchas as well. Like I said, non-trivial.