Comment 4 for bug 1741447

As a workaround I enabled low graphics mode in a terminal, and rebooted

    nano ~/.config/upstart/lowgfx.conf
    Paste this into it:

start on starting unity7
pre-start script
    initctl set-env -g UNITY_LOW_GFX_MODE=1
end script

    Log out and back in

https://insights.ubuntu.com/2016/09/19/low-graphics-mode-in-unity-7/

At least you can do something, but it's buggy as hell.

So I consider moving back from HWE kernels to default 16.04, because I feel it was caused by the latest libgl1-mesa / xorg updates