So I thought that a desktop environment could be nice and installed mate.
But I wanted to start it from emulationstation, so I edited some stuff analog to how you would set up kodi, made a screenshot to use it as the background inside es and got the mate logo from wikipedia.
You can now start it from es and logging out will bring you back to es.
In the zip file is everything you need to set it up.
The wallpaper is this splashscreen.

Edit: the second zip file is identical to the first one, but I have no idea how to remove it.