Wayland!

Run GUI Apps As Root

Okay, so this doesn't work by default for a reason. It's a bad idea to run GUI apps as root, as it gives them access to X.org/Xwayland/Wayland/etc. But, if you MUST do it (*cough* MATLAB *cough*), here's how:

Allow Root Control of Wayland:

xhost si:localuser:root

Revoke Root Control of Wayland When Finished:

xhost -si:localuser:root

Guake F12 Toggle Doesn't Work!

This is a problem that occurs when Guake is installed on Wayland. It occurs because Guake can't add register the default keybinding with GNOME. You can fix this by adding it yourself:

1. Open the GNOME dash and search for "Keyboard." Open the keyboard shortcut settings.
2. Scroll to the bottom and create a new global shortcut:
   1. Name: Guake
   2. Command: guake -t
   3. Shortcut: F12

Source for this one here.