When I connect to my first client and use full screen, I can disable it using the keys CTRL-ALT-Shift-F no problem.
But when I open a new client within the first client and go full screen I loose VNC menus and the trick with keys only affect the first client. It is virtually impossible to get out of full screen from within a VNC client.
How I can go back to normal view on my second client?
I'm not sure but if you using RealVNC as the second client you could try to press F8 key for menu access.
thanks Anton for your feedback. Tried that also not working :(