Desktop Settings are accessible by right-clicking on the desktop, but not accessible through the System Settings app. It seems to be that it belongs there, also. I was looking to change a certain KDE behavior (scroll-wheeling on the desktop switched virtual desktops, and I triggered that by accident a lot and didn't like it). So I went to System Settings and looked all over for somewhere to change this behavior. When I couldn't find it in System Settings, I presumed that I had exhausted the possibilities. Only after asking on IRC was I made aware of another set of settings not accessible through System Settings. Reproducible: Always
*** This bug has been marked as a duplicate of bug 235294 ***