anchor.diff:  
          invalidForeignTilesCnt:=MaxInt;
          invalidNativeTilesCnt:=0;
  +       centerPosValid := false;
   
           for i := 0 to rect.FWidth - 1 do
           begin
  
positive.code:   nativeTestStrongOk: Boolean;
    dirtTestOk: Boolean;
    sandTestOK: Boolean;
  begin
    Result.result:=false;
    Result.flip:=0;
  
negative.code: 
      // Special validity check for rock & water
  
      if valid and (curTile.TerType in [TTerrainType.water, TTerrainType.rock]) then
      begin
        for pName in WATER_ROCK_P do
        begin
  