Yeah, all Desktops look like this now (if you can say that).
Ok, will do this weekend. If that doesn't fix it, I'll be in touch. Thanks for now.
Had I given up after reading this (AMD Radeon OpenCL), I wouldn't have to reinstall now. Sadly, I was too motivated that I could get it to work.
I'll mark your second message as solution, since this was originally about me installing lightdm on Core.