Upgraded to Linux Mint 16 Petra

I upgraded my Linux Mint 15 installation with Linux Mint 16 via Package upgrade. There I followed the instructions from "Upgrade Linux Mint 15 (Olivia) to Linux Mint 16 (Petra)"

It's easy but I ran into a problem.
So after that:

sudo sed -i 's/raring/saucy/' /etc/apt/sources.list
sudo sed -i 's/olivia/petra/' /etc/apt/sources.list
sudo sed -i 's/raring/saucy/' /etc/apt/sources.list.d/official-package-repositories.list
sudo sed -i 's/olivia/petra/' /etc/apt/sources.list.d/official-package-repositories.list 

sudo apt-get update && sudo apt-get dist-upgrade
sudo apt-get upgrade  

It took a while and after the reboot (used
sudo shutdown -r now
because the dialog to restart was no longer readable), I ran into a requester saying "There was an error loading the theme BlackNBlue".
Yes, you guessed it, I installed a theme on Olivia and it didn't survive the upgrade. I couldn't log in, and there was no way to getting to the GUI. So I started an editor and changed the HTML-Theme to "Clouds" at /etc/mdm/mdm.conf (see screenshot).

After another reboot the login-screen appeared and worked as intended.

However, I found the settings and panel-entries for the settings were all doubled. One started the gnome-control center and the other the cinnamon settings. I edited the menu to get rid of the gnome-panels. Uninstalling would have brick some of my installed programs, which might be the reason they are here at all. 

So no big deal in the end, and now I'm enjoying a new Mint system, hopefully without the "Dummy Output" sound bug appearing randomly after booting, like Olivia did.