That looks like the walls around the grate are not textured - which makes the engine cover the hole because such constructs (albeit with deeper holes are often used as rendering tricks.
You are correct. My bad.
BTW, turning the center hud messages option off, does not seem to do any good as the print statements are still being displayed in the center which is not what the hexen.exe does (it shows centered at the top(out of the way)).