Maybe it is my windows setup, but from the list of levels in the top pane it is hard to see which one is currently in view. I would even say it is impossible to see as all tabs in it seem have the same color.
Is it possible to better highlight the active level?

Also when right clicking on the ...

Looks good to me and I don't understand why elevated lines would improve this. But that is probably because I don't know what you want to achieve.

There is a way to elevate polylines but maybe it's a bit cumbersome if you need many different elevations: use elevated levels for those polylines you ...

https://marcel.mesa.nl/seethome_leidingen.jpg Hi Puybaret,
They may be flat bit the they have a with, and are visible in 3D.
See this wiring picture that is build of polylines only (build could look much better with elevated lines...;)

(and maybe a future version might add thickness to a polyline ...

Off coarse we can get rid of all models, options, methods and objects and build everything using walls, rooms and boxes as bese items, export them and impport then as furniture ;) Sort of the differnece between RISC processosr and and Interl processor...

The thing is that polylines are there ...

yes, but the beaty of polylnes is that you can make a connected graph so when you move one point, the edges move along. It is also easy to split line segments or delete points.

I still think it would be great to integrate the wirings plugin and polylines features, hence extending polylines with an elevation parameter. I.e. promoting polylines to 3D objects...

Nice improvements!
Wouldn't the changes to dimension lines (elevation) also not make it easy to create 3 dimensional poylines (i.e. adding elevation to each of the polyline points). Guess that would also make the 3D-wiring plugin much simpler and beter integrated with the core SH3D.

line a few of them up and create groups. that would at least simplify things a bit

Using polylines I mapped all (actully not finished yet) electric, ventilation, water, and floorheating pipes in the floors/ceilings in Sweethome3d plan...

I played a bit with version 3 of the plugin.
I works reasonably good! A few remarks

- when I change the thickness of the polyline it does show the change in plan view, but not in 3D view.
- when I use the 'edit points' and delete or add a point from a wire (by accident or deliberate), I cannot add ...