xtightvncviewer hangs when returning from full screen

Running Xubuntu 16.04 on both client and server. Server is a laptop running `x11vnc -display :0 -forever`. From client, I connect with `xvncviewer $hostname`. Connects fine, everything works great. Press F8 on client to bring up the pop-up menu, and all options work as expected. Click on Full screen, and that too works.

However, when I want to get out of full screen mode, I press F8, click on Full screen again and something hangs. The Full screen option in the menu disappears, and nothing else works, I'm left staring at the server screen, but I can't do anything. I can move the mouse pointer which is now just a dot, but clicking does nothing, and because I was in full screen, I can't access anything else on the client machine, even via Alt-Tab.

Changing to the console and killing xvncviewer doesn't help, and in the end I have to restart xorg. Please let me know if you need more info to help debug this.