No matter if 'Dual Monitor: Use second monitor' is checked or not, the full screen view always opens on the monitor XnView starts on.
For example:
- XnView main window last used on the left monitor.
- When restarting XnView the next time, it will show up on the left monitor again (as expected).
- Fullscreen view opens on the left monitor too.
- Move XnView main window to the right monitor (without closing it)
- Fullscreen view will still open on the left monitor.
As I don't expect that to be a feature, it must be a bug

Or do I misunderstand the setting?
Merry Christmas and a happy New Year!
Lorenz
PS. sorry for the duplicate post in 'Classic - General Support'. I somehow landed there after login.