anchor.diff:  
   function TEditTerrain.MapRect: TMapRect;
   begin
  -  Result.Clear();
  +  Result.Create();
     Result.FWidth:=FMap.Width;
     Result.FHeight:=FMap.Height;
   end;
  
positive.code:     and (Bottom()>Other.Top())
      and (Other.Bottom()>Top());
  
    Result.Clear();
  
    if intersects then
    begin
  
negative.code: type
    { TMapRect }
  
    TMapRect = object
      FTopLeft: TMapCoord;
      FWidth,FHeight: Integer;
  
      constructor Create(); //empty
  
      function Left(): integer;
      function Right(): integer;
  