This looks like a fun corner case:

What I expected to happen was...:
Join a minecraft multiplayer server and switch to full screen

What actually happened was...:
Crash screen

Steps to Reproduce:
1. set pc up with one monitor, start minecraft, go to server selection
2. plug in second monitor (my notebook is set up so that this monitor becomes the new primary screen and minecraft is now on that screen)
3. join a server
4. instantly after clicking join, press F11 to switch to fullscreen
5. MC stays in window modes, goes black and after a few seconds crashes.

I can reproduce this reliably right now, no plugins installed. Switching primary screen seems to be nessesary