While using Tmux, I tried to maximise the current pane using
<prefix> z, and had a bit of a keyboard fail and accidently held down the prefix keys while pressing z, instead of letting go of the prefix combo. The terminal then cleared completely (maximised, clearing all my panes), and while I was able to type into it, I wasn't able to escape or use any shortcut keys to get out of this.
Does anyone know what this mode is and how to get out of it? To recreate, hold down your prefix keys and press 'z' (while the prefix keys are still held down).