Going good I see. The operator puzzles me. Sorry, no idea how to fix it.
It's only a warning so there is no need to fix it. But a funny thing is that I need to fix something I wrote in 2009 when I did the SDL port. It's the way areas of screen are updated. At that time I just updated everything but doing that can make the game slow. It's better record the biggest area and update it once when waiting a key press (which is probably the easiest way to check it, since everything is turn based). There is also a delay routine (for some kind of animations), but you can just add the same check in there.