Create a line with staff line thickness

I am trying to create a user defined line with the staff line thickness but it seems that there’s a limit in the thickness that does not allow to reach the 1/10 thickness (the default staff line thickness). In this picture I show my line over the middle staff line, and it can be seen that it is slightly wider:
Is there any way to get this?
Thank you inadvanced!

The default staff line thickness is 1/8 spaces, not 1/10 spaces. The default “solid line”, for instance, has a thickness of 1/8 spaces.
I’ve just tried changing the staff line thickness to 1/10 spaces, then editing the default “solid line” so that it uses a line body with 1/10 thickness, and it works absolutely fine.
Are you sure you’re editing the same line body as the one you’re using within the line?

Thank you pianoleo! The problem was that “line body editor” does not select by default the “line body” which is defined for the line you are editing, and I changed the value of the wrong “line body”. Now it works perfectly!