Would it be possible to make a solid Bar over the entire underground distance? Sometimes, the small square is hard to see.

Hmmmm. Thinking about it for a moment I think it would be possible, but I'll have to look into it.

Thank you.

So I had another look at the modding system since it's been a few years, and it doesn't look like it's possible to achieve this. It goes back to a similar problem as this previous thread: https://mods.factorio.com/mod/show-max-underground-distance/discussion/5ee2e835885dc5000c79b9a7 which also was asking about a larger range of displays. Essentially, because the way the system - and therefore mod - is set up, it needs the sprites to be pre-made at launch and connected using an offset, which leads to all kind of weirdness when said sprite is larger than a single tile (rotation, clipping, etc.). Sorry.

Thanks for looking at this. I guess this is something the Game Developers need to fix.