This change implements the desktop cube effect using QtQuick 3D. It's a much simpler version of the old desktop cube effect. You can rotate the cube and click LMB to switch to the currently viewed virtual desktop.
Keyboard navigation is simple too:
Escape - quit the effect
Right arrow keys - rotate the cube left or right, respectively
Return - switch to the currently viewed desktop
The cube effect reserves
Meta+C keyboard shortcut. You need to have at
least three virtual desktops in order to activate the effect.