Hi Lars,

> Ah, that's good to know, since it doesn't look that
> way when hiding the edges.

Try selecting those surfaces and use Edit/Join to glue them together at their common edges.

If it won't glue together, then that would mean that the edges are too far apart.

Once joined you should get a better display at those areas when you hide edges because the generated meshes will have a unified structure along those edges.

When you have 2 surfaces that are just sitting next to one another but not actually joined, then the meshes that are created from them (which is what you see being shaded there) can have slightly vertex placements there, making it look like there are cracks and gaps between things. But that's just a display artifact from meshing.

- Michael