under list in the main xml you have a line wich starts with color. make the colour for Back and the colour for gridlineback the same
Yeah, this did the trick. I hadn't got a value for "GridlineBack" in my Main.xml. Neither in "noire", where I couldn't even see a difference between color 1 and 2, nor in "Aruba", where I could see the horizontal gridlines as you can see on my pic. I just had to add the value "GridlineBack="xxyyzz" to the color line you and Beatnik mentioned and it works fine.
I think there should be another way to reach the goal, because "aruba" does it without having this value, but I don't care
Thank you for supporting me with this!
I created a modified version of Noire's main.xml file a couple of months ago. It has a bit darker gridlines, but unfortunately I don't remember what I changed. The file is in the attached zip file if you want to compare it with the original. (Maybe you could report back if you find the difference.)
I tried this out, but it didn't have an effect... sorry, but the horizontal grids stayed invisible for me. There was no "GridlineBack" value in your version. Adding this did the trick with your file also.