advanced coastline mappaint style

[Klumbumbus]

I was thinking about displaying the sides of a coastline in the mapview because errors in the coastline can cause big rendering issues. (We also have such renderings for cliff, embankment, kerb, retaining_wall.) Possible solutions could be:

• blue right-casing and brown left casing
• image pattern with waves at the right side

However we already have validator warnings for coastlines and I do not know if an advanced paint style would be distracting. Coastlines are also often together with boundaries and landuse borders. Since I do not have experience with coastline mapping, I'm not sure if it would be helpful or painful. Any opinions?