I tried setting up a macro using AutoKey and assigned `Ctrl`+`Alt`+`f8` thinking it probably wouldn't be used for something else. Unfortunately it turned my entire screen black except for a cursor in the top left corner! I found a mention of that function [here](https://askubuntu.com/questions/252929/ctrlaltf8-pulls-blank-screen-what-is-this-for).

Where can I find a list of key combinations that are unused (assuming there are any)?