On Kubuntu 17.10 with backports KDE 5.12.3: in system tray I click on Networks > I click on button to "Configure network connections..."> I want to add a vpn connection: I spent more than an hour to figure out that the "+" button to add a new connection is at the bottom of that editor. For some reason I had first not scrolled completely down to the bottom. Please fix this extreme userunfriendliness. Even idiots should be able to figure it out quickly (and this idiot is using Linux for 17 years and at my job (already 9 years) most of my work is done on Linux). The fact that this editor has a vertical and a horizontal scroll bar is part of the reason of my failing to find the hidden button. Did I mention the amount of frustration I felt about the bad design of this program?
The plus button is a pretty standard user interface convention for "add something to this list." The real issue here is that it's not visible until you scroll down to the bottom. The UI is currently being redesigned, so I'll make sure this issue is addressed.
*** This bug has been marked as a duplicate of bug 389585 ***