My last comment was on a work computer w/ Ubuntu 16 and Cinnamon. On my home computer with Mint 18 + Cinnamon, I started having problems after mono-complete was installed.
I did:
apt remove mono-complete keepass2 apt autoremove
reboot
mouse focus started working again.
apt install mono-complete keepass2
mouse focus still working
My last comment was on a work computer w/ Ubuntu 16 and Cinnamon. On my home computer with Mint 18 + Cinnamon, I started having problems after mono-complete was installed.
I did:
apt remove mono-complete keepass2
apt autoremove
reboot
mouse focus started working again.
apt install mono-complete keepass2
reboot
mouse focus still working