I start the vncserver using a -geometry argument with a size bigger of the
physical screen. Then I start vncviewer with a command like this:
  vncviewer -remoteresize=0 -fullscreen :1
Normally because the size of the vnc window is bigger of the physical screen,
only part of the vncserver window is visible. But if I move the cursor close to
the edge of the screen, the vnc window scrolls showing the hidden section.
Scrolling has worked up to Leap 42.3 but it doesn't work in 15.0.