I'm in KStars Build: 2019-10-03T08:23:19Z on my desktop right now. On my laptop (build in signature, more frequently used), I have my artifical horizon functioning just fine. I can't save it, however, because I get the wonderful invalid polygon error. I surely must have succeeded in the first place with it by luck, because I can't recreate it in my desktop without getting the invalid error, weather by manually typing out the points or drawing it, or even drawing some random would-be restricted area.
When I try to create another one on my laptop, it doesn't even mind that my new drawing is probably going to fail, it's concerned with the old polygon (which displays perfectly and doesn't touch the horizon at all, nor does it end with a zero, it only begins with a zero in the altitude).
Further, when I was typing in some of the points, I could type "39" and then hit space- the cursor would not advance for two lines of points, but on the third it went back to normal behavior.
Now I don't know if the whole "first and last points must be on the horizon" just happens to be required to allow the function to exist, but I'm drawing the thing in the first place because I don't see a horizon where my scope stands, at all, and I'm even further restricted by trees and buildings, so of course that requirement was odd in my perspective from the beginning, but there must be some way by which that requirement can be ousted? I mean, my art.horiz which is actually working doesn't come close to the horizon, so why require two points to be as such? I'm sure it's technical, so I assure you the question is rhetorical.
I didn't find a video on the process, but I think it would be a quick and valuable addition to the tutorial video lineup. The KStars Handbook (pg.48 of who knows what version- could use a version/date on the first page) directions for art.horiz doesn't really reflect the issues I have personally seen with the tool, and so I've listed them here.
Tired and a little cranky (probably much of the moon and cloud effects), but thought it useful to list out the issues I've seen with this tool over the past week. Can I even incorporate it into Ekos? I don't think so, and if not, consider it a point on the wishlist for sure.
The cool thing is, I somehow have it working on the machine I use the most- I don't know how. The lame thing is, I can't do anything else with it or duplicate it or further understand it.