Hello,
I just installed Mint 19.1-Cinnamon (Tessa) and then kde-full on top of it. I did the same under Mint 19 (Tara) and everything worked o.k. - then. Now, on the contrary, when I select "Plasma" when booting, the desktop comes up, but it "limps" (golly, does it limp!). I cannot do things like moving windows around or changing their size. I wonder what's wrong. Has anybody had the same experience?
Thanks for your help
H. Stoellinger

Hello,
I purged Cinnamon, then also KDE-full, then re-installed KDE-full. The effect was the same.
Installing KWIN solved the problem. Is KWIN not included in KDE-full? If not, it should be!
Regards
H. Stoellinger